Wanting to play Civilization VI but need 1G GPU. Is this possible?

Hello, My wife bought me the new Civs game to play on our iMac but it seems the graphics card isn't up to snuff. The Mac plays Civs V fine on highest video settings but for whatever reason, they require an insane performance upgrade with the new game even though graphics seem lesser on the quality side... Anyway, I'm either needing to upgrade my current system, or, but a new one. I was curious if i could put a mid 2010 27" GPU(Pictured) in if that would work. I know Macs are picky son thought i'd better ask first. Any suggestions? Thank you!