Worth upgrade from RTX 3070 to 3080ti or 3090?

im also thinking about the RTX3090 or 3080Ti. the price difference here is $400 CAD which is what i paid for my 2080S 2 years ago. i already upgraded my processor to 5600X and it gave me a good improvements and I can play on mostly high and some ultra settings on 4K monitor without problems at 30FPS with A32NX in LAX with FSLTL. idk if its worth the upgrade as people say this game is mostly CPU limited. my CPU usage is mostly around 30% in LAX with the first thread at ~80% usage, but FPS still shows CPU limited message. I have the most used cores overclocked to 4.8Ghz. GPU usage though is always fluctuating in DX11 and i cant figure out why, and with DX12 enabled GPU load is higher near 90% mark now. VRAM is almost always at 99%. I really want the 3080Ti to save some dough but i dont want to upgrade if the improvements are small and maybe save for the 4090 next year.