It looks like Ubisoft might provide Xbox One X gamers with the option for 1080p 60FPS in Assassin's Creed Origins, with YouTuber "DEE BATCH" nothing that Ubisoft said during the Fan Expo Canada event that the studio is working on a 1080p 60FPS option for Xbox One X.
Assassin's Creed Origin is the largest open world game ever created, so it'll be interesting to see how many dials and options Ubisoft has had to turn down in order to hit 60FPS @ 1080p. We should expect Assassin's Creed Origins to use dynamic resolution scaling to reach their designated 4K 30FPS, so we could expect the resolution to drop as low as 1080p in order to keep things from becoming a chug fest.
The PS4 Pro version of Assassin's Creed Origins might feature a 1080p 60FPS mode since Sony added more grunt into the PS4 Pro, but the Xbox One X has a much better GPU that could handle 1080p 60FPS a lot easier. Remember both consoles have that junk Jaguar CPU from something like 44 years ago or something, so the big difference between the Xbox One X and PS4 Pro comes down to the GPU grunt and bandwidth.