I use my computer for gaming, school work, and typical random shit. Typically seeing CPU temperatures 38C idle and 65C while playing CS or PubeG. GPU around 40 idle and 55-60 while playing either of those games. Occasionally I play other games, but those are what I usually play, so it's not like I need a super computer.

Was thinking to upgrade case fans from the pos rosewills that came with it (which I really havent had any issues with, but I'm ready for a change).
Eventually will want a high(ish) capacity HDD. Maybe 4TB WD Black or something like that.
Would MOBO upgrade help my 3060ti with PCIE 4.0?
Not really interested in 1440p because I like my 24inch monitors.

What do you think my current bottleneck would be?

The cpu

I assume ill need a mobo upgrade to go with that since any cpu upgrade I make that’s fine on the same mobo would probably be a minimal upgrade.

If I were to upgrade CPU what would you recommend I go to?

5600x

You're already using an 8-core processor...which is equal to the Ryzen 5800X.

The 5600X is a 6-core processor...

And you don't need a motherboard upgrade. You may need a motherboard BIOS update to use the new Ryzen 5000 series.