Yes, Taron Egerton has the range. If you recall, he starred in Sing, in which he played a gorilla who would rather be a rock star than follow in his gangster father's footsteps, and during the movie's climax, he actually sings the classic Elton John song "I'm Still Standing." He and John have known each other since the singer had a cameo in Kingsman: The Golden Circle, and Kingsman director Matthew Vaughn announced that he was interested in perhaps producing the long-gestating Elton John biopic, as long as Egerton was in it. A few months later, negotiations were done, and Egerton signed on, stepping into a role that, in the past, had been circled and contemplated by the likes of Tom Hardy and Justin Timberlake.
Since then (ramping up after Bohemian Rhapsody became an Oscar contender, and eventual winner for Malek), the stars have done all they can to emphasize the fact that it's Egerton's voice you'll be hearing belting out "Tiny Dancer," "Bennie and the Jets," and the rest. He clangs "Crocodile Rock" while nearly doing handstands on his piano during his first concert scene, croons "Don't Go Breaking My Heart" in a recording studio with Kiki Dee (played by Rachel Muldoon), and even shares a duet of "Honky Cat" with Game of Thrones' Richard Madden. Egerton and John recorded a new song together for the movie's soundtrack called "(I'm Gonna) Love Me Again." They even shared a duet at the afterparty of Rocketman's Cannes premiere.