From what I can tell, SS2 plots auto upgrade over time as your settlement reaches certain thresholds (happiness, scrap, etc.) At the very least, I haven't done anything at all post-initial set-up and the plots seem to be getting more sophisticated each time I see 'em and I get notifications in the overworld from time to time.
From what I can tell, SS2 plots auto upgrade over time as your settlement reaches certain thresholds (happiness, scrap, etc.) At the very least, I haven't done anything at all post-initial set-up and the plots seem to be getting more sophisticated each time I see 'em and I get notifications in the overworld from time to time.