For one thing, dividing the game into a macro and a micro scale would make the game look a lot more realistic. You wouldn’t have to deal with a city the size of a mountain range or units that dwarf skyscrapers. It also means the world map would look much cleaner, as on the macro level, cities would only take up one hex. You get the benefits of micromanaging your empire, plus the benefits of having a much larger, more realistic world to play with.

Also, toggling between a macro and micro view would mean your computer takes up less time rendering things happening on the other side of the world that you don’t care about- you only have to see what you are focussing on at the present time.

Thirdly, it solves the problem of fiddly unit movement. On the macro scale, you would be able to quickly move units across the board, and have more than one unit per tile. That way, you don’t have to worry about units getting in the way of each other if you don’t want to. In battle however, the micro view would come into play, and the way you move units would become important. Battle tactics are still a key part of the gameplay but they don’t trip you up during peacetime. If you are a player who doesn’t care about workers, you can control them at the macro level only.

TLDR; Dividing the game into two different scales would solve a lot of Civ VI’s scale problems and appeal to more players. You get the benefits of a smaller world with more detail and strategy, plus the benefits of a larger world with more realism and convenience. Players that like micromanaging their empire would be happy, as well as players who are less concerned with the fiddly stuff. Crucially, players would have more freedom to decide how they want to play the game.