system agnostic – Looking for kingdom building resource that includes attracting a populous

My GM gave my character land for a barony. However, there is currently not much there and they did not give me any rules for building it up. One thing they tasked my character with was attracting the population that will live in my barony.

I’m looking for sourcebooks or rules sets for ruling and constructing a kingdom. Particularly I’m looking for some that that:
Give rules for small scale holdings (a barony within a kingdom not necessarily the whole kingdom)
Anything on immigration or population transfer.
Anything on attracting cohorts to your kingdom/holdings.

I’m playing pathfinder 1e. The setting is Mystara. But I’m fine with rules from whatever system since I’m just looking for inspiration to suggest some things to the GM. I am aware of the pathfinder kingdom building rules and they are not what I’m looking for in this instance.