I wanted to ask about this too. It occured to me later that these could be like settlement specific or something maybe. Like predefined stuff for different locations? ie the boat in Kingsport Lighthouse being a predefined element there like a "Kingsport Plot" if that makes sense. Like a unique placeable plot only usable in Kingsport that is placeable in water. Maybe I am overthinking it?
Yes, predefined, location-specific city plans are the only way this could work. I don't think you will have to place them. It will probably be manageable through the city manager's desk, or some special, central ASAM sensor? Lol, maybe it's an ASAM sensor snapped to the workbench.
From what I understood, modders will be able to create additional city plans so that you can choose. I hope it will be possible for mod-added settlements, too.
What I wonder about is: will these city plans have slots for regular plots, or will that stuff be included?
The city plan could just have some beds integrated with it, for example.
Or certain residential blueprints at specific locations, without a way to change.
Or, it could have residential plots at certain places, which cannot be moved or removed, but the blueprint can be changed.
Or there are just 2x2 snappable surfaces or holes there, and you can put in whatever you like?