Since everyone is engagement baiting claiming Chris Evans is playing "evil Steve Rogers" or Hydra Cap, this is how Steve Rogers plays into the plot of Avengers: Doomsday and he's the same 616 Steve you've known since The First Avenger:
In Avengers: Endgame Steve goes back to 1947 to be with Peggy. Since he wasn't supposed to do that, it'd create a branch timeline that the (pre-Loki Season 2) TVA would prune.
At some point after his son James is born, TVA Loki (again before the end of Loki Season 2) comes to him to explain the situation to him. But since he's Steve Rogers and saved the universe with the Avengers, Loki offers him something of a witness relocation to a universe where there is no Steve Rogers. He sends Steve, Peggy, and James to 828 (the F4 universe) where the three of them live in peace for a decade.
What Loki didn't know is that someone being in a universe they don't belong causes an Incursion. Someone who has figured that out is Doom, who has been studying Incursions for a long time and has deduced that the next one is going to hit 828. He goes to Reed to see if they could find someone who doesn't belong in their universe, which leads them to Steve.
Doom has a plan (of course it's a diversion from his real evil plan) to stop incursions but they need to go 616. They take Steve with them because he can convince the heroes of Earth to go along with Reed and Doom's plan.
The "miracle" Thor is talking about in the trailer isn't Steve. It's about the plan to stop the universes from colliding into each other as the death of every universe is a bigger threat than anyone has ever faced.