How to get 40+ yield on a district?

[Yzman]

Do these 4 tiles have to be in the same city or spread across multiple cities? I believe the earlier task where you have to have 4 specialists, those have to be in the same city, so I’m not sure.

Not same city, but that task requires different tiles with specialists. It isn't technically required however to complete the full path you will need 4 tiles anyway.