At what distance are you comparing the games? You do know that the extra resolution from 4K is not visible unless you're at 3 feet or less with a 55 inch TV?
With the PS4 does the text look bigger in the game than the PS4 Pro? If yes, then you're at 4K on the Ps4 Pro, and the game is patched. That the games will look better at 4K is entirely subjective, and depends on the game. Simply adding resolution doesn't mean there's extra details.
Here's a list of patched games and the extras:
http

/www.gamespot.com/articles/every-ps4-pro-game-that-is-and-isnt-getting-an-upg/1100-6443385/
4K doesn't mean the games will look different. The difference will be minimal.