Question XFX Radeon RX 580 8GB Graphics card

When you say "GPU settings" what are we talking about?

If you mean in game settings (things like shadow quality, that sort of thing) then as @Frag Maniac says it will depend on the game.

You could try using the "high" preset in most games (maybe "medium in some modern AAA titles), and then adjust settings up or down depending on how it performs.

There are also articles on line that discuss performance in specific games. PC Gamer, Techpowerup, and DSO Gaming are some of my go-to sites for that. e.g.

If you mean settings for the graphics card itself e.g. settings in the graphics card software, then generally you might leave them to default unless there is a specific issue you need to deal with.