CryoByte33 on YouTube[0] has videos explaining in details different configuration presets to run games like God of War, Witcher 3, or Breath of the Wild.
He's also maintaining an impressive piece of software[1] that helps optimize your Steam Deck.
Worst case scenario, if you don't find the game you're looking for in his videos, chances are you will find a decent configuration on SteamDeckHQ[2]