As a pop star, Olivia Rodrigo wields a rather unusual arsenal of weapons. She is an acute writer and an un-self-conscious singer. She largely abhors artifice. She is modest, not salacious. In just three years, she has achieved something approaching stratospheric fame — a four-times platinum debut album and a Grammy for best new artist — while somehow remaining an underdog.

But the weapon she returns to again and again is a very pointed and versatile curse word, one that she used to vivid effect on both her 2020 breakout hit, “Drivers License,” the first single from her debut album, “Sour,” and also on “Vampire,” the Grammy-nominated single from her second album, “Guts,” released last year. It’s in plenty of other places, too, giving her anguished entreaties an extra splash of zest. She wants to make it clear that underneath her composed exterior, she’s boiling over.

On Friday night at Acrisure Arena in Palm Desert, Calif., during the opening performance of the Guts World Tour, Rodrigo couldn’t get enough of that word. She used it for emphasis, to connote dismissiveness and to demonstrate exasperation. But mostly she used it casually, in between-song banter, not because she needed to, but because using it felt like getting away with something.

Much of Rodrigo’s music — especially “Guts,” with its detailed and delirious ruminations about new fame and its discontents — is about how it feels to act bad after being told how important it is to be good. It’s situated at the juncture where freedom is just about to give way to misbehavior.

This was true of her performance as well, which brought the perfection and order of musical theater to the pop-punk and piano balladry that her songs toggle between. Over an hour and a half, Rodrigo alternately roared and pleaded, stomped and collapsed. She led a reverent 11,000-person crowd — a sizable leap from the theaters she played on her first tour — in singalongs that were churchlike and raucous, but never rowdy.

Throughout the concert, Rodrigo made gestural nods to abandon — singing the first verse of “Get Him Back!” through a megaphone, knocking the mic stand down at the end of “All-American Bitch,” performing spicily for a camera peering up from beneath a clear section of the stage on “Obsessed.”

While she has an exuberant stage presence, she is not a full-service pop star, and is better for avoiding that trap. Rodrigo is on her surest footing when performing faithful, unflashy recitations of her songs. She opened the night with a boundlessly energetic “Bad Idea Right?” followed by “Ballad of a Homeschooled Girl,” perhaps the truest statement of purpose from her last album, and let the dry, groaning ’90s guitars telegraph anxiety and gloom.

Those songs emphasize Rodrigo’s yen to rock, which is earnest and studied and bolstered by an impressively roaring band that lent her a soupçon of grit. But she followed with an even more powerful troika of howling repudiations: “Vampire” into “Traitor” into “Drivers License,” a string of slow ballads that are among her most invigorating songs. (Almost as moving was hearing three young girls, maybe 8 years old, screaming their brains out to “Traitor” while watching its music video in the back of a tricked-out Mercedes Sprinter van in the parking lot before the show.)

But making her songs feel big didn’t require much besides the songs themselves. At the end of “The Grudge,” Rodrigo stood pointedly alone at the foot of the stage, a flash of self-sufficiency and defiance. (Dancers joined her for several songs, and for some, she danced along with them awkwardly.) Late in the performance, she sang a gasping “Happier” and the casually sinister “Favorite Crime” while seated at the edge of one of the stage’s tentacles. And although she was floating over the crowd on a crescent moon for “Logical” and “Enough for You,” two of her most heartbreaking songs, it was the firm quiver in her voice that thrilled the most, not the spectacle up in the air.

In her outfits, Rodrigo leans into a combination of demure and tough. Her fans have been taking note. In the crowd, there was near sartorial unanimity — young girls, mostly teenagers, in midthigh skirts and either black boots or Chuck Taylors. Almost everyone had at least one item that sparkled. It recalled early Taylor Swift tours, where young fans arrived in sundresses and cowboy boots by the thousands. At one point, Rodrigo asked the crowd if anyone had come with their father (many), then if anyone had come with a boyfriend or girlfriend (not many). Then she asked if anyone had dressed up for the show, and the crowd roared almost in unison. (Women outnumbered men so significantly, most of the men’s restrooms were converted to all-gender for the night.)

At the merchandise booths, vendors were selling the accouterments of girlhood: lavender butterfly-shaped tote bags, star-shaped stickers that adhere to your face (to emulate the “Sour” album cover) and Band-Aids with Rodrigo catchphrases. And onstage, the performers were advertising the power of girlhood: the members of Rodrigo’s band and dance troupe were all female, nonbinary or transgender.

Rodrigo has made supporting young women part of the tour, too: Proceeds from each ticket go to her charitable organization, Fund 4 Good, and will support “community-based nonprofits that champion girls’ education, support reproductive rights and prevent gender-based violence.”

That’s in keeping with Rodrigo’s enduring and persuasive narrative that girlhood is fraught. Her rendition of “Teenage Dream,” a ballad about wondering whether the best years of her life are already past, was particularly revelatory, especially with the backing visuals of Rodrigo as a young child toying around with performing, unaware of the realities of stardom.

The opener was Chappell Roan, a sexually frank singer whose big voice was obliterated by her arrangements. She offered a contrast to Rodrigo, who sings about sex in glancing references and punchlines, often hidden in the middle of a verse. (Beginning in April, the openers will be Remi Wolf, PinkPantheress and, very promisingly for the cross-generationally curious, the Breeders.)

That subject matter is still too raw for Rodrigo, who never places herself too far away from her youngest fans, or her younger self. But that might change soon. Rodrigo turned 21 a few days before this show, perhaps the final publicly acknowledged demarcation line between youth and adulthood. She did not let it pass without comment.

“I went to the gas station the other day and bought a pack of cigarettes,” she said, sitting at the piano after “Drivers License,” in what threatened to be the night’s sole moment of genuine misbehavior.

But then she confessed, “I promise I didn’t consume it, but I just bought it just because I could.” Did she add a curse word for emphasis? She fudging did.