What kinds of games do you play?
Some are cpu limited like sims, mmo and strategy games.
Others like fast action shooters like strong graphics cards.
Multiplayer likes many threads.
To assess, try this simple test:
Run YOUR games, but lower your resolution and eye candy.
This makes the graphics card loaf a bit.
If your FPS increases, it indicates that your cpu is strong enough to drive a better graphics configuration.
If your FPS stays the same, you are likely more cpu limited.
Your cpu upgrade on the current motherboard is limited to the i7-7700K, perhaps a 10% boost.
$75 or so on ebay if you want to try it.
Current intel or amd is otherwise the way to go.
If you need stronger graphics, tom's gpu hierarchy chart gives you some sort of upgrade capabilities.
6700XT is already a strong card, upgrading will likely also need a new psu.