Total War is an outlier in that genre, I didn't realise it was one of the games you would be playing, it's one of the very few higher graphics fighting RTS's around, most are low graphics tactical gameplay.. kinda like how Total War used to be... ah RTW you beautiful ******* - in that case you should get a 6600xt or 7500xt still...
People completely overestimate the importance of a graphics card for tactical/rts games, literally for all those you mentioned earlier and any paradox game, an onboard graphics card is good enough and any proper desktop graphics card will be completely cpu bound. My rx 470 8GB is cpu bound in all the games you mentioned originally and pdx games, and I can play Total War just fine, all at 1440p.
Everyone is saying the same thing here, but you really want a 7700xt, so that's the card you should get