Red Dead Redemption 2 seems, as is the custom with the majority of major third-party releases, to have a deal going on with Sony, and as has been the case with all the game's trailers, the recent gameplay reveal was also entirely captured on a PlayStation 4 Pro. This time around, a little technical detail about the game was let out too.
In the blog post announcing the gameplay reveal trailer on PlayStation Blog a text snippet says:
"Captured entirely from in-game footage on PlayStation 4 Pro, watch this introduction to Red Dead Redemption 2's gameplay in 4K."
So we can likely count on the game to run in 4K on the PlayStation 4 Pro. The piece did not specify however whether this is a checkerboard solution, or if it is indeed native.