Is my CPU first thing to upgrade?

Money was an issue when I built my PC so went a touch above a budget build during cyber Monday sales. Money sitch is better and PC is getting slow

so wanted to upgrade a little.

Country: Australia

Budget and currency : $800aud max

Resolution; QHD or below (my eye sight is shit so not too fussed on going to UHD)

Current specs:

Processor - 12th gen Intel R core i5-12600k

Ram - 2x16

Graphics card - Intel arc b580 12gb

I'm still new to this so please let me know if I need to provide any more info.