Yes to all 3! I really want the game to have a scenarios and also a way to play in a specific eras.

Another feature that I think can be made into a mod which can suit the custom scenario idea very well is to limit the number of district you can build per era.

This prevent players from infinitely expanding their cities taking over too much spaces which breaks the immersiveness for scenarios.

Instead, the player can be focusing on infrastructure which often conflict with district building in the current state of the game. However by limiting the number of district many other aspects of the game are also impacted namely some infrasturctures, era stars and civs. Therefore I imagine if this feature is to be made into the game, we need an overhaul mod but keep the city building feature in the vanilla game for players who enjoy playing that way.

I agree, there should be a limit on how much you can expand your cities. In Humankind the world turns into ecumenopolis way too fast and this breaks the immersion.

It wouldn't be an issue if the maps were at least 5 times bigger than they are now. Overall, developers of 4X games really needs to start making maps much, much bigger. The current systems just doesn't work well with the current map sizes.

Bigger maps please