Use combinations of scaling, moving, etc. to adjust accordingly. Depends on the specifics of the conditions. What happens when you adjust the width and length? Do internal rooms stay the same size? Are some rooms favored over others? Are there limits? Do doors move? Do windows move? There are many questions you need to ask yourself in this problem (much of which are asked in BIM, I’d suggest looking at how something like Revit deals with resizing of rooms and then start embedding that logic into your system)
However, as I said earlier, it makes more sense to define the floor plan as a parametric system rather that try to adjust a static floor plan parametrically.