This Seeking Tech guide will explain how you can enable PlayStation Spectral Super Resolution (PSSR) on the PS5 Pro version of the Resident Evil 4 Remake.
This feature is only available in the High Frame Rate Mode. In order to turn it on, you need to take the following steps:
Use the following video as a visual aide:
Go to the Title Screen. You won’t be able to change the graphics mode while playing the game.
Next, you need to go to Options.
You should then switch over to the Display tab.
Finally, turn on the High Frame Rate Mode to also enable PSSR.