Sims appear to be grainy/pixelated?

AThirstyMonster  Your hardware all has the max rating except for the CPU, which shouldn't affect how the graphics work.  I poked around a bit in GraphicsRules.sgr and saw some settings that I don't completely understand, in that they could be referring to different user settings, but you don't need to edit this file to experiment a bit.

First, please remove Options.ini from Documents > Electronic Arts > The Sims 4, so the game creates a new one with all default settings.  Don't change anything; just load CAS and have a look.  When you're done, you can trash the new file and restore the old one to have all your old settings back.

If that doesn't help, try setting your user DPI scaling to 96 (100%), just as a test.  Here's how:

https://www.elevenforum.com/t/change-display-dpi-scaling-level-in-windows-11.934/

Restart your computer after changing the setting and before trying to play.  If the desktop icons are too small for you, that's fine; just revert when you've finished looking at the game.