Since that monkey wearing glasses stole my moment of glory, im gonna use this moment to reccomend the mod Sim Settlements, now there is even an expansion for it, called Rise of the Commonwealth, that allows to let somebody else (the AI) in charge of your settlement and it will expand and build semi randomly , also it will manage itself.
Sim Settlements is a Mod for Fallout 4 that allows you to build zone objects that tell the settlers what type of buildings to create in different areas of your settlement and they will do so. Includes a progression system, a more interesting settler needs system, and rewards to help settlements matter more.
Official web: https://www.simsettlements.com
In Nexus: Sim Settlements at Fallout 4 Nexus - Mods and community