This can be seen first hand with Beijing+Tianjin versus Hebei.
Those 2 cities were under direct State Council control so it was easier to push economic reforms versus a largely rural province like Hebei, plus they were close enough that it made sense for anyone half ambitious in Hebei to leave for the big city than to stay back.
This is what happened in NY State as well with NYC and IL with Chicago. It's called primacy effect in economics.
The issue is, research into stuff like this and converting it into actionable policy is becoming difficult, as mid and lower level civil servants don't want to deviate from a literal definition of policies or their mandate as administrations have become much more vindictive due to the economic slowdown. Research like this ends up stepping on people's toes.
http://www.kjjb.org/EN/abstract/abstract18771.shtml
http://www.progressingeography.com/EN/10.18306/dlkxjz.2019.0...
https://www.sciencedirect.com/science/article/pii/S187705092...
https://www.sciencedirect.com/science/article/abs/pii/S02648...
https://www.npr.org/sections/parallels/2017/04/16/523632920/...