Hi, depending one the amount of objects and the type of visualization, i use 2 methods:
First one, and its probably the more straighforward method is simply make the objets in the floor below appear in the upper floor with the plan and section dialog. You can make slabs and walls appear in the next floor and works relatively well for simple things. Dont forget to adjust your plane cut heights in your view map! Also, dont forget to use cover fills for your slabs, so you dont see whats below.
If you need more complex visualization, i would recommend creating a cloned folder of the plans, and also create a specific layer combination and graphic override for it (which would allow you to see everything in gray outlines, or whatever color you want). This plans will be used only for seeing whats below your current plan.
Then in the layouts, you sticht your current floor plan with the lower floor cutting out the portions you dont need. You have to do this once and its a bit tricky, but once is done it works great and you can control how you see everything.