The Xbox Series X is a more powerful console than the PS5. Whether this means better graphics in games, is a different story. It is more likely that if there is a difference between the two, the Xbox Series X version of the game will run at a higher framerate or at a higher resolution rather than having any additional rendering features or higher quality textures.
If any games are going to be better, they will be the first party games that Microsoft developes to take advantage of the extra power and will not be held back by the PS5. Since these games are not going to be on the PS5, we can’t really say they are better, but this is the most likely scenario.