Sims 4 RTX 2080 Super low GPU usage

@CevenKills  Well, you got your card recognized, at least.  That's what the [Found: 1, Matched: 1] values mean in the config info.  You might want to keep a copy of graphicscards.sgr, or at least copy the edits, in case your card still isn't added to the database with the next patch.

Do you get any improvement switching among fullscreen, windowed, and windowed borderless modes?  One of them might give you better results than the others.

The last thing I can think of to try is a clean boot.  No Afterburner, no other monitoring apps, just Origin and TS4, plus Origin's fps monitoring if you want, or the game's own version.

https://support.microsoft.com/en-us/help/929135/how-to-perform-a-clean-boot-in-windows

If the game runs better, then you'll have the dubious pleasure of sorting through your other background apps to find the issue.  If this were TS3, I'd start with various Windows game functions, like fullscreen optimization and Game Mode, although those tend to work better with TS4.

If you still get wild fps swings even with a clean boot, then maybe it's some combination of the game and your very new, very powerful card.  I'm still not sure it should be working as hard as you imagine, although I don't have a 2080 Super to test on myself.  (I can ask other people with good cards what they see, just to get a baseline.)  The game may be better optimized for high-end systems once 32-bit support is dropped, some time in the near future.  But it's not clear when that will be, or whether you'd see any improvement.