One of the great advantages of PlayStation 5 (and Xbox Series) is that you can play games from the previous generation without having to buy it again. Not only that, but those games also make use of the stronger hardware, although it varies from game to game to what extent that makes a difference.
In the case of Ghost of Tsushima, it makes all the difference. Digital Foundry explains this in a new video. The game benefits greatly from a higher frame rate of 60FPS compared to the 30FPS on PlayStation 4 Pro. There are some snags to that, which are demonstrated in this analysis video.