INDIO, Calif. — A sandstorm whipped dirt and dust into eyes, mouths and all over the bodies of thousands of people. The sky was hazy. Powerful winds had the palm trees flailing all over the place, and the heat reached nearly 90 degrees at times. But not even unfavorable weather conditions could harsh the vibe of this year’s attendees at the Coachella Valley Music and Arts Festival.

“I, like, cried yesterday out of happiness. Being back here, I forgot that this was normal,” said Chelsea Bazilian, 29, a therapist in Los Angeles, who wore a long pastel pink wig and a black minidress that exposed her stomach.

Various groups of friends sat together on the vast lawn, chatting, leaning on one another. One young woman, wearing a sparkly sheer sarong and not much else, stood in the middle of it all, her back to a camera while a friend eagerly snapped pictures of her rear end.

The mood at Coachella this year was that of total joy. The famous music festival in the harsh California desert — which started in 1999 and has featured performers as wide-ranging as Nine Inch Nails and Beyoncé — returned after a two-year hiatus because of the coronavirus pandemic without masking, testing, or vaccine requirements, radiating with what felt like a pronounced shift toward vibrant positivity.

“It is fun and optimistic, and maybe there’s a change for good happening,” Ms. Bazilian said.

Held over this weekend and last, this year’s festival featured Harry Styles, Billie Eilish and Swedish House Mafia with the Weeknd headlining. (Kanye West was also originally scheduled to play, but withdrew.) The pandemic hasn’t ended, but with the widespread availability of vaccines and less deadly variants emerging, hordes of young people buzzed around the festival.

In the center of the activity stood a giant cylindrical structure, checkered with multicolored glass. Attendees wore all sorts of flamboyant attire: cowboy hats and boots, transparent lace pants, makeup that looked like it could have appeared on “Euphoria,” brightly colored bell-bottoms, Dennis Rodman T-shirts and leather harnesses. They danced, joked, French kissed, sucked on nicotine vaporizers that looked like pacifiers, photographed themselves and ate $11 slices of pizza.

An idea has been percolating, coined by the trend forecaster Sean Monahan and later popularized by the writer Allison P. Davis in a viral article published in New York magazine earlier this year, that we have arrived at a moment or “vibe shift” when a new era of cool starts emerging.

Trends are slippery things that consistently resist our best attempts to define them — particularly these days when any “-core” can go viral on TikTok, distorting our ability to determine what has mass popular appeal. Whether Coachella still has relevance is up for debate. A recent poll on Deuxmoi, a popular celebrity gossip Instagram account, asked if, after this year, Coachella as a “whole is over.” Sixty-seven percent of respondents said yes. The festival, nevertheless, is an ideal place to see thousands of young people having a good time while trying to be cool, to be free, to feel alive.

The vibe of the outfits at the festival was, unsurprisingly, skimpy. Fashion elements from the 1970s, like bell-bottoms, mashed up against early 2000s fashion like low-rise jeans, bellybutton piercings, and big cargo pants. Unlike in years past, there were no flower crowns or white people in Native American headdresses to be found.

The key shift seemed to be in the energy. In spite of all the reasons for pessimism (climate, war, inflation, Covid-19), attendees seemed hopeful, positive, sanguine.

“We were so inhibited from full expression because of Covid,” said Pierce Nasser, an actor who lives in Los Angeles. Mr. Nasser, 27, wore transparent pink sunglasses, with pearls stuck to his face, a massive neckpiece also made of pearls, and bright green bell-bottoms.

Bright, vivid colors are in, he observed: “Because of the rise of magic mushrooms, that’s giving people this trippy psychedelic vibe.” (Over the last several years, using psilocybin mushrooms has become increasingly accepted as a wellness practice, thought to help with depression, and mushrooms themselves — the non-psychedelic kind — have gained popularity as an aesthetic motif.)

“Now that things are starting to open again and we’re getting to be with other people, there’s this explosion of expression,” Mr. Nasser said.

So what was totally out of style? The behaviors we’ve carefully observed over the last two years, like social distancing, wearing masks and worrying about contracting Covid. The festival felt like a sort of coming-out party for 20-somethings who, until now, were tragically cooped up during their prime partying years.

Lafonzo Spigner, 23, who came from Tulsa, Okla., and who uses the pronouns they and them, appeared to be having a blast: gregarious, smiling and topless, with braids that fell all the way down their back, parted in the middle. The only piece of clothing on their body was a skirt made of Polaroid pictures of their own body parts, held together with chains. Every few minutes, a stranger would approach to gush about their get-up.

The “two years of internal thoughts and internal dialogue” during the pandemic, they said, allowed them to get to know themselves better, and Coachella was their opportunity to debut their full, honest self: mostly nude and unapologetically ostentatious. “When I meet people and interact with people, I go 110 percent Lafonzo,” they said. “It’s liberating.”

Hipster cynicism also seemed officially like a thing of the past. At Coachella, partyers in their 20s expressed a desire to move away from what they saw as the dark energy permeating the American psyche over the last six years, in favor of harmony and love. After all the isolation, many attendees said they were excited about togetherness and being unapologetically yourself.

“After Covid, I learned to embrace my uniqueness,” said Paris Tomassian, a 24-year-old nurse who wore a platinum wig and a get-up that she described as “futuristic cowgirl.” “Covid taught people to be more empathetic to others, to appreciate life more, to take care of each other,” she said, adding: “I feel like Covid sort of unified everyone.”

Madison Burk, a 21-year-old college student in San Francisco, said that she experienced some “trauma” during the pandemic, like many others. Despite all that, she said that “the only way not to be optimistic” about the future “is if you’re holding on to the past.” Her friend Biruk Tewodros, 20, added, “Envision and make a better future for yourself.”

In an interview, Mr. Monahan, the trend forecaster, said it was not surprising to him that optimism was trending just as early 2000s fashion is making a comeback. “I watched a lot of early 2000s movies during the winter before I wrote the ‘vibe shift’ thing,” Mr. Monahan said. “I was watching ‘Charlie’s Angels’ with Lucy Liu and Drew Barrymore, and it feels like a really different country. There was a level of optimism that you rarely see in any pop culture anymore.”

Mr. Monahan also noted that, in general, “In the U.S., people are optimistic about their personal fortunes and pessimistic about general outcomes.”

But back at Coachella, Dominic Garza, 25, a college student from Los Angeles, who is studying political science, was feeling optimistic about more than just himself. “Our generation is going to be the one to fix everything,” he said. “Our generation is more open-minded.”

Mr. Garza wore an embroidered denim jacket with matching jeans, several beaded bracelets, silver necklaces and no shirt, and exuded a soothing kind of warmth. He said that seeing Harry Styles perform and be “comfortable with his femininity” was “freeing.” (In early 2021, Mr. Garza came out to his parents as bisexual, and at Coachella, he finally got the opportunity to present himself to the world, he said.)

It’s not just changing gender and sexuality norms that have Mr. Garza feeling positive about the future. Speaking about the way older generations understand current events, he said, “All these things are at the level of, ‘It’s doomsday! The world is ending!’” he said. But growing up during the Iraq War and the 2008 financial crisis, and then spending his late teens and early 20s in a fractious political climate and a pandemic, have taught Mr. Garza to be resilient. “I feel like we’ve learned that we’ll get through it no matter what,” he said. “It’s not as dire as they want us to think it is.”

Young people have always been more bright-eyed and bushy-tailed than their older counterparts, the stereotype goes (and there’s plenty of data to back it up). Still, one might think that coming-of-age at a time when nearly a million Americans have died from Covid, and young people have spent their youth in lockdowns, would make these 20-somethings more cynical than previous generations.

“There’s a lot of things to be pessimistic about,” Mr. Garza acknowledged. “But at the same time, technology is always advancing. Humans are very innovative. A lot of our problems, I trust that we’ll find the solutions for them.” Generation Z, he said confidently, will do “a better job” at addressing global problems than the people in charge now.

Of course, this may or may not be the case, but the children twirling in the desert, who are at least a portion of our future, do seem to feel this way.