Even before Billie Eilish took home five Grammys on Sunday, she had already won the night, at least as far as the game of super-one-upmanship that is the red carpet was concerned.

She did it not by opting out, like Alicia Keys (who also wore four different looks in her role as host, plus a fifth one to perform) or the presenter Cynthia Erivo. She was perfectly willing to play the game: to show up relatively early in the parade, to pose for the paparazzi, to enlist a big brand (Gucci).

But in doing so, she also changed the rules and thus swept the field — much as she does with her music and her approach to stardom. It was a fitting choice (no pun intended) on a night that took place in the shadow of Kobe Bryant’s death, and in an arena that, as Ms. Keys said in her opening speech, “Kobe built”: the Staples Center in Los Angeles.

Because what Ms. Eilish did not do was engage with the two most common stereotypes of female celebrities on the red carpet. She didn’t play the siren, all va-va-voom curves and legs, like Camilla Cabello in a short, strapless LBD — with sheer ruffled overskirt — by Versace, Saweetie in sparkling body-skimming Moschino, or even Lizzo, in white strapless Versace (white was the color of the night).

She didn’t offer an implicit homage to J. Lo’s 2000 Grammys-breaking navel-plunging Versace, like Priyanka Chopra and Chrissy Teigen, cleavage spilling forth.

She didn’t play the fairy tale princess, like Ariana Grande in a titanic Giambattista Valli tulle creation and long opera gloves (later swapped for an emerald green Cinderella Givenchy) or Demi Lovato, performing in yards of white satin. And she didn’t retreat to the safe option: the Marlene Dietrich-defined tuxedo suit.

She never does. But attending her first Grammys, and after telling Elle that once she turned 18 (which she did last December), she might start being less covered up, it was possible she might have changed her signature.

As if. Instead she walked the red carpet in an oversize black bowling shirt patterned with sparkling chartreuse double GGs, over matching baggy trousers and atop a high-neck, billowing-sleeved chartreuse shirt. Also, a matching patterned face mask. And dyed-to-match two-tone hair. And long, filed to a point, green Gucci nails. (Nails were another thing.) She was happy to dress up, and even engage with some classically feminine (if slightly scary looking) beauty tropes. Just on her own terms.

When she changed for her performance with her brother, Finneas O’Connell, they each wore matching baggy cream Gucci suits (hers more baggy than his). Later, for the after-parties, she changed into yet more enveloping Gucci.

Just as Billy Porter has blown through the borders of what men should wear on the red carpet — this time around he was like a crystal-strewn disco cowboy in a mechanical hat dripping diamanté fringe — Ms. Eilish is expanding expectations for women.

Last May she talked, in a Calvin Klein campaign, “I Speak The Truth In #MyCalvins,” about why she chooses to wear body-swallowing clothes, saying that it was so no one could have an opinion on her body — could critique or celebrate it — because they “haven’t seen what’s underneath.” That she was keeping it a mystery to avoid the usual (often negative, pretty much always irrelevant) commentary, and to focus attention instead where it belonged: on her music.

And yet, for a public figure to say her body is not public property is still a pretty radical act.

Especially in a world where conventional wisdom about female appearance is still steeped in role play established long ago; especially at a time when the Harvey Weinstein trial is unfolding in New York and the question of “Can a woman be president?” is still creating controversy. It’s also an important statement.

Just as with Ms. Eilish’s songs, it’s time has come.