Any number of Civs & City-states regardless of map size

[achiafo]

One feature I miss from Civ V, is the ability to set the number of city states/civs to however many you wanted. Even if I wanted to play against 16 AI opponents on a small map, I could do it. I'd like to see similar implementation in Civ VI, and hopefully it would be something easily moddable. Any help appreciated!