Alright, after some discussion outside of Stack Exchange, this is the full solution. I've taken the liberty to put together a quick scene as a demo.
Method 1: Only for top-down view.
In the case where you're only interested seeing the floor layout from the top down view, adjust the Clipping Start Distance for the camera until you're seeing just what you want.
This gives a result like this
This will only work if you're only interested in seeing the floor layout from the top view only. If you're trying to view it from an angle, using the clipping settings will turn out like this:
Method 2: View-able from all angles, only works with cycles.
The process to be able to view the floor layout from all angles is a bit more involved.
The first thing you want to do is to duplicate and hide your house and all the objects within it. This is just to keep the original ones as a backup. If you've kept all your objects neat and tidy within collections, you can just right click on the collection and Duplicate Collection.
Now with the duplicate collection, right click on it, press Select Objects, and then press Ctrl+J to join the entire house and its furniture into a single object. If you've got any modifiers on the objects, you're going to want to apply them before joining them together.
Now add a cube, and apply a Boolean intersect modifier to the house with the cube as the target object. Resize the cube such that it intersects with the parts of the house you want to see. This can be done more easily if you set the view port display of the cube to Bounds. Also disable the cube in renders so it doesn't get in the way.
Now if you render, you'll get something that almost looks like our desired outcome. The only issue now is that the ambient lighting from the sun is no longer being blocked by the roof, since the Boolean operation had removed that part from the house.
Go back to your original object, and duplicate the walls and roof again. Feel free to join these two objects together. For these duplicates, go to Object Properties > Visibility > Ray Visibility, and disable Camera. This will cause these to affect the lighting of the scene, but not actually be visible in it.
And with all that, you've finally arrived at a floor plan that can be viewed from all angles. By animating the Boolean intersect cube, you can change the cross-section during an animation, with the proper lighting as if your entire object was still there.