As far as I know there is not a way to drag a box and just rebake the current selection.
What you can do (which is what I do in my projects, is divide your projects up in parts and move every part to a seperate layer.
If you make sure that you have your light setup in the top layer (which should always be on) you can then hide certain layers with geometry that you dont want to re-bake.
I usually put the foundation (walls, ceilings etc.) of my apartments on one layer, and make a seperate layer for each room that contains it’s furniture.
I know its a messy work around, and it doesnt always work in every situation, but it can be useful for some projects.
You can read more about this layer system here: World Composition User Guide | Unreal Engine Documentation