Red Dead Redemption 2 has been confirmed to run in 4K on both Xbox One X and PlayStation 4 by both Microsoft and Sony, respectively. This 4K confirmation came after Rockstar released the six minute long gameplay trailer yesterday.
Confirmation about Red Dead Redemption 2 running in 4K on PlayStation 4 Pro can be found on the official which reads "Captured entirely from in-game footage on PlayStation 4 Pro, watch this introduction to Red Dead Redemption 2’s gameplay in 4K", with the aforementioned trailer embedded.
Official shows a similar message, stating that Red Dead Redemption 2 will be an Xbox One X Enhanced game and it will support 4K resolution along with HDR, for the TVs that actually support them as well. Microsoft did post a disclaimer that Xbox One X Enhanced features are a "subject to release of a content update".
PlayStation 4's blog description also suggests that the footage shown in the gameplay trailer was captured on a PlayStation 4 Pro in 4K. Rockstar Games later confirmed this to be true in an interview with US Gamer. Therefore, no downgrades should be expected and PlayStation 4 Pro owners can look forward to performance just like on the trailer footage.
Meanwhile, Xbox One X owners will likely get the same performance out of their consoles but it is unclear whether it will be like that on release, due to the disclaimer I mentioned above. Xbox One X Enhanced features might in fact come at a later date as a part of a content update. Maybe Microsoft should really focus on delivering the best experience to their customers instead of calling Sony out for blocking cross-play between the consoles.