You cannot change Diablo Immortal PC resolution, atleast not yet

Diablo Immortal is out now, with full support for mobile gamers worldwide. PC players can also play the game too, however, the PC client is a little
PC players are finding that you cannot alter the Diablo Immortal PC resolution, at least not yet

I tried playing Diablo Immortal on PC, and it was a mistake

Clans and Warbands Guide for Diablo Immortal - Wowhead

Diablo IV Beta showing some problems with FSR 2.0, particularly with fine lines. Taken using 6900xt : r/Amd

6 Improvements Blizzard Needs To Make To The Diablo Immortal PC Beta

Diablo Immortal Review - Evil On The Go - GameSpot

All Soft and Hidden Caps

Please Blizzard, do something! : r/DiabloImmortal

Diablo Immortal Tips Guide: 9 Things the Game Doesn't Tell You

Diablo Immortal (for iOS) Review