Depending on placement, it’s often possible to raze several of the captured cities and just reincorporate the territories as part of your existing cities. At least on the maps I’ve played it always seems like I wish most of my cities could add one or two extra territories before the cost gets too ridiculous. This gives you that room to grow.
The other big thing is that it uses a version of the territory system they created for Endless Legend. So there are defined territories on the map that can’t contain more than one city each. In addition to that, cities can add neighboring territories into them rather than founding new cities on top(as mentioned above, the city cap is pretty tight for much of the game). You’ll be building a lot of districts on the map(like in Endless Legend, not really like in Civ 6) so incorporating the territory allows a city to expand districts into those territories to exploit whatever resources.