If you own the PS4 and PS5 versions of the same game, here's how to switch between them:
  1. From the Games Home Screen, go to the Game Library.  
  2. Select the game and press X 
  3. Select the [...] button on the screen to view options.  
  4. Select the version of the game you want to download or play.
Note: If you are unsure of what version of the game you are viewing on this screen:
PS4 versions display PS4 beside the game title at the top of the screen. PS5 versions only display the game title.