Ive worked out a couple of setting combinations for you to choose from, but first, the basics.
Ah, but which options to use?
First off, head to the Controls menu and switch the Button Icon jot down to jot down 2.

Otherwise, it will default to the very much non-matching icons of thePS5 DualSensepad.
Next up, the visuals.
Sadly, its impossible for Resident Evil 4 to cement a solid 60fps on the Steam Decks hardware.
As Leon would say when faced with a similarly overwhelming sense of grief and regret: Oh, no.
Or, if you want to stay well clear of the 30fps waterline, there is an alternative.