Not definitively — he's in a deadlocked competition with Deshaun Watson for the job.
As of late May OTAs, OC Travis Switzer said neither QB has pulled ahead — both are splitting first-team reps and making equal progress learning Todd Monken's offense (from the Shedeur Sanders page). A May 1 report suggested Watson was leading the competition and that ownership was pushing for him to start, but that hasn't resulted in a clear winner yet.
The Browns have a crowded QB room — Watson, Sanders, Dillon Gabriel, and rookie Taylen Green are all in the mix, making it one of the messier situations in the league. Until someone separates himself, Sanders is a candidate to start but far from locked in.
On The Fantasy Headliners, they noted the Browns spent premium draft capital on WRs KC Concepcion and Denzel Boston, suggesting they're trying to build around whichever QB wins the job — but they didn't call Sanders the favorite ().