Extrude up the walls.
Punch out the doors and windows.
Design generic door, window, sink, toilet and shower,
or find them in a collection, maybe convert from ACAD,
Copy and derive specific instances of each.
Stick em into the openings.
Create roofs, soffits and stairs as slabs.
Texture and glaze according to need.
Then you can do landforms, plantings and paths.
Simulate lighting and stuff at will. etc...

If that seems like a bit much, there are
architectural modeling programs such as
in order of decreasing excellence (debatable):
Revit, Architectural desktop, ArchiCAD, CA etc...

Lots a luck