Devices sharing Apple IDs: what credentials can an user with an iPad PIN use?
You have some limited control by enabling a couple toggles.


Require password for all purchases, every time or use family sharing to restrict the ability of that iPad to get new downloads from the managed / signed in account of your choice. - https://www.apple.com/family-sharing/
Sign out of all and any cloud services you don’t trust them to not delete things (they can delete anything you can delete - photos, contacts, mails) so them reading the information is not the worst that can happen.


You might be able to use parental restrictions / guided access to lock one app in the foreground, but I would just say - have them get a used device or you get a used device and just let it be community / no accounts / require password to purchase or make a “children” account for the shared device and enroll AppleID in family settings so you have to explicitly approve all purchases on that secondary ID.


https://support.apple.com/HT202612