Yes, those rental properties will show up on FAFSA. Assuming that you have enough rentals to live comfortably, that will likely put you in a place that will make need based aid very difficult to attain. If the school of choice uses the other financial formula (name escapes me at the moment, but commonly used by Ivy leagues and other 'public ivies') then even more assets, or a greater % of assets, will be admissible.
I'm a financial advisor, but we paid an outside firm specializing in education funding to consult before my oldest graduated HS in 2023. It was worthwhile for us, if for no other reason than to understand why some numbers are counted an others are not. The company we engaged was College Planning Associates, but they subbed out the financial analysis to another firm.
Ridin' 'cross the desert. . .