LAS VEGAS >> Sir Elton John gave actor Taron Egerton some unlikely advice for portraying him in “Rocketman”: Don’t do an impression. Sing the songs the way you want.

It was a freeing, if unusual, bit of direction for a project about himself that John had been trying to make for seven years. But it gets to the heart of what “Rocketman,” out on Friday, is trying to do: Evoke the essence of John’s life, as told by John, from his childhood to middle age and all the success, tumult and darkness behind all those fantastical costumes, and not give audiences a Wikipedia entry.

You won’t even hear John’s voice at all — Egerton performs the songs himself. It’s an unconventional biopic for an unconventional rock star and John, 72, certainly wasn’t going to get in the way of that.

The project itself came together in a roundabout way, after a few years of false starts. At one point, Tom Hardy was actually signed on to star. But it wasn’t until producer Matthew Vaughn — who is friends with John and his husband David Furnish and had convinced John to do a cameo in his “Kingsman” sequel — proposed the idea of Egerton that things really started moving forward.

Director Dexter Fletcher said it was the “idea of Taron playing Elton that ignited it for me.” He’d worked with the actor before, on “Eddie the Eagle,” and knew he had the vocal chops to do it and the daring to be able to “go there” for an R-rated musical.

In “Rocketman,” there will be rock and roll, drugs, sex, rehab and an exploration of John’s relationship with his then-manager John Reid, who is played by “Game of Thrones” alum Richard Madden. In other words, “Bohemian Rhapsody” this is not.

“It’s where they didn’t dare to go on ‘Bohemian Rhapsody,’ where they didn’t want to go,” said Fletcher, who was actually the one who finished the Oscar-winning Freddie Mercury biopic after director Bryan Singer exited. “It’s part of Elton’s life. He wears glasses. He plays the piano. He’s gay…I saw it as an opportunity to look at that. It’s responsibly and creatively and respectfully handled and I’m really happy with what we’ve done. I think it might make a difference.”

FOR EGERTON, 29, the opportunity to play John was a “surreal dream,” if a little daunting.

“I’m a big believer in doing things that scare you and it is intimidating but I wouldn’t have done it if I didn’t feel it was a good candidate for the job,” said Egerton. “I always felt that it had the potential to be quite special.”

He plays the music icon from around age 17, when he’s still going by Reginald Dwight, to age 43. To prepare, he trawled YouTube for old clips and acquainted himself with some lesser known songs, but he knew that there was a limit to what he’d be able to glean from the public record — in part because the film shows John at some of his darkest moments, which weren’t exactly happening when the cameras were on.

Egerton found that he learned the most by getting to know John himself.

In fact, Egerton has become good friends with John over the past few years, starting with his “Kingsman” cameo, evolving to their first one-on-one outing for takeaway curry, and culminating into a relationship where they now speak most days.

“He’s great fun,” Egerton said. “He’s a great raconteur and he’s very funny. And he’s very interested in me as well.”

They even have been known to give each other gifts. John gave Egerton his first diamond earring (which Egerton wears for the rehab scenes). Egerton, in return, got John’s prescription added to the glitzy glasses he wears in the scene where he’s writing “Your Song.”

“He’s worn them a couple of times since, which really touched me,” Egerton said.

As with the singing, Egerton had the freedom to put his own spin and interpretation on things.

“It’s a fantasy creation,” he said. “When you see the film I hope I am recognizable as him. But it’s undeniably me as well.”

IT’S WORTH reiterating that this is not even attempting to be a documentary. As Fletcher says, John is telling his story from memory, and he’s a “slightly unreliable narrator.” So the costumes aren’t carbon copies. He didn’t really levitate on stage at The Troubadour (nor was he clean shaven). And don’t expect to learn any dates (there are none included).

“He is the rocket man. You can’t be pedestrian with your storytelling when you’re making a movie about a rocket man. … It’s a little psychedelic, elevated and kooky,” Egerton said.

And while the laws of gravity aren’t necessarily applicable here, there was one rule he set for himself: You will never see him miming any songs. Most of the time, he’s actually even singing in-camera.

Aside from the spectacle of the songs, the heart of the film, for Egerton, is John’s relationship with Bernie Taupin, his longtime lyricist who is played by Jamie Bell.

“It’s a platonic love story between Elton and Bernie,” he said.

He remembers asking John what it was like when he met Taupin.

John told him, “It was like meeting the brother I had never had. It was someone to go to the cinema with,” Egerton said.

Egerton and Fletcher are eager for audiences to see it.

“Some things you do for love and some things you do for money,” said Fletcher. “We set out on this to create something that we will love in 50 years’ time.”