If we believe how Civ 6 works, basically people toil on farms and mines (mostly mines) forever. There's not much room for scientists and engineers. Currently, there is very little reason to actually grow cities as long as they hold the districts you want and the tiles you want to work. Improvements are pretty weak IMO and that's another topic, but older civ games had better ways of you of taking advantage of population that's not tied to the land. The problem is they moved GPP to the buildings and the amount of citizen slots is not much (only 1 per building). I think it'd be a good idea to buff the amount of citizen slots and maybe adjusting specialist yields by a bit. This would be better than just straight up buffing specailists and making it better for you to grow cities. The disadvantage of course is the added micromanagement requiirement but the auto function already does an adequate amount, and "focus science " seems to work. I think this would be a much better solution for catering to people that want to build huge cities, and certainly much better than "I liek playing tall, you should be kicked in the groin every time you capture a city"