I Downloaded it myself and have about 5-10fps in the main menu on a RTX3090 64GB , 3950X. Most of the reviews say the same. Colossal Order are suggesting you should play on very low detail. I was a massive fan of the original having played Sim City since 1993 but I cant even get into this. It shouldnt have been released so early IMO
It sounds like the best thing to do is follow the patientgamers approach for CS2.
Check back in 18 months and see if it is worth the cash then.
It is an excellent approach for most recent games, but a must for paradox ones.
And for all releases of Civilisation. Wait till at least the second expansion pack before purchase.
I give it 6 months but I'm just on low dose copium.