Blizzard will soon roll out a new update for Diablo 4 (Patch 2.1.4), and one of the key changes is a new default setting for resolution scaling on PC.
Once patch 2.1.4 is live, the game will automatically choose a resolution scaling method based on your system’s hardware. It does not matter if that is DLSS, FSR, or another method, the game will automatically try to strike a better balance between visuals and performance without requiring manual setup.
This change mostly affects Diablo 4 PC players. On consoles like PlayStation 5 or Xbox, resolution scaling settings are usually baked into the game’s config files for those platforms, so there should be no noticeable difference there, even on newer hardware like PS5 Pro.

Blizzard has not said much yet about a dedicated PS5 Pro patch, though some players speculate it may already be active or coming soon in a future update.
You can find the official Patch 2.1.4 notes here:
Diablo IV Patch Notes – Blizzard Official