Scattered throughout his studio, the executive producer of the “Barbie” soundtrack — and a musical polymath known for his work with artists like Amy Winehouse and Lady Gaga — has a few “leftovers” scattered across the room. One doll is placed in a permanent split, stretched across a Moog synthesizer. Another is styled to look like primatologist Jane Goodall.

“I went to Toys R Us and I couldn’t find a single Ken,” he laughs. Fittingly, “that’s the theme of the movie.” Mattel HQ did end up sending over a few; the Ken that remains in Ronson’s studio is, appropriately, shirtless.

Finding the sound of “Barbie,” poised to become one of 2023’s biggest blockbusters, required careful consideration and research for a film with such a rich visual palette. In the end, he produced a stacked soundtrack that included Lizzo, Billie Eilish, Dua Lipa (who also acts in the movie) and more.

But it started with a simple text message.

The music supervisor on the project, George Drakoulias, shot Ronson a quick, “Barbie?” Ronson read the script and was in. He also scored “Barbie” with collaborator Andrew Wyatt. Ronson is no stranger to working on music for film, but executive producing a soundtrack album and scoring an entire movie, let alone, a movie of this size, was new territory. “It was a lot of learning on the job,” he says.

The soundtrack assignment began with two tracks: a pop song for a big dance number and an ’80s power ballad for Ken (name a genre with more “self-aware, bombastic silliness,” as Ronson calls it).

The former came first. Ronson came up with a chorus and beat — a detour from his first, far too obvious plan on writing “’80s, sugar-y pop,” and instead landing on a “groovy, melodic thing … with some toughness,” perfect for Dua Lipa. It became “Dance the Night,” the Lipa track featured in the film’s main trailer.

The Ken song came about differently. For the most part, Ronson works on instrumentals: When he wrote “Shallow” with Lady Gaga and Bradley Cooper for “A Star Is Born,” for example, he only contributed lyrics to fill in gaps — the “surface, don’t hurt us,” line, as he recalls. But for the song that would become Ryan Gosling’s “I’m Just Ken,” Ronson couldn’t shake the lyric: “I’m just Ken, anywhere else I’d be a 10.”

So he sent director Greta Gerwig a demo with a few lines — including a deliciously mouthy lyric about “blonde fragility.” She sent it to Gosling, who plays Ken in the film, and knew immediately he needed to sing it. What could have soundtracked any scene in the film became its own musical moment.

Early on, Gerwig used the Bee Gees and ’70s discos as a reference point for Ronson.

“You know the Chicago (Disco Demolition) thing, where everyone burned their disco records, “Saturday Night Fever” had reached its apex and the poor Bee Gees were like, ‘All we wanted to do was make people dance! What did we do wrong?’” says Ronson. “That’s ‘Barbie.’”

If anything, that idea is more of a thematic one than a sonic guideline. The mood board was vast, and also included “Dolly Parton, Olivia Newton John, ‘Nine to Five,’” Ronson explains.

It speaks to why the “Barbie” soundtrack spans pop genres, including a reggaeton track courtesy of Karol G, “Watati,” bubblegum K-pop from girl group Fifty Fifty featuring Kaliii in “Barbie Dreams,” and the falsetto-led piano ballad “What Was I Made For?” by Billie Eilish.

For Atlantic Records, who released the soundtrack, collaboration and diversity was key.

“All of these artists were brought in early on to do screenings with Mark, Greta, and the filmmakers. They would see scenes they were going to write their music to,” says Brandon Davis, executive vice president and co-head of pop A&R at the label. “Each of these artists wrote lyrics about the specific ways Barbie was important to them.”

Ronson echoes the sentiment.

“Karol G was like, ‘I’m here because I love Barbie. I wasn’t expecting this incredible film. This is awesome,’” he says. “And HAIM had this encyclopedic knowledge. The only VHS they were allowed in the ’90s, when they were kids, was this one Barbie thing. They knew every song.”

Others were tasked with a prompt: Lizzo’s “Pink”, which ends with a voiceover from Helen Mirren, was inspired by the lead Barbie, played by Margot Robbie, living through her perfect day. And because the film is a comedy with real-world complications, humor informed a lot of the songwriting: It’s in Dominic Fike’s “Hey Blondie” as well as the many samples of Charli XCX’s “Speed Drive.”

“(Soundtracks) are an area where we cracked the code and figured out how to make it work in a way where we support our partners creatively,” says Kevin Weaver, president of Atlantic Records West Coast, citing Atlantic’s work on other major soundtracks like from the “Fast & Furious” franchise, “The Fault in Our Stars,” and “ The Greatest Showman,” which produced massive hits like Wiz Khalifa and Charlie Puth’s “See You Again,” Charli XCX’s “Boom Clap,” and “This Is Me,” respectively.

But unlike those films, part of the acquisition process for “Barbie” required a trip to the doll factory, where Atlantic executives got to witness the doll-making process from inception to completion. (Davis and Weaver are both producers on the soundtrack.)

When working with legendary intellectual property, a soundtrack comes with some risks. Do you bring back Aqua’s 1997 hit “Barbie Girl,” or do you reimagine it? Surely Nicki Minaj must be featured — her fans are called Barbz.

“I remember — no offense — that I had a song on the “Ghostbusters” remake and I think six of the 12 songs were reinterpretations of Ray Parker Jr.(’s “Ghostbusters” theme),” says Ronson. “It all dovetailed into the single we have with Nicki Minaj and Ice Spice,” he continued, referencing the reworking of “Barbie Girl.”

“I’ve never really executive produced something before,” Ronson says. “I love this film. We had an amazing partner in Atlantic Records.”

“And then doing the score, but it was a lot of learning on the job. It was still a job that I’ve never really done before. … It’s fun to show people different scenes and getting them to dream big.”