How to grant access to all site data but disallow list modifications

I’m creating a SPO site that will serve as the backend for a PowerApp. Several lists will have item level permissions so that only users who created the data will be able to view it. The app will have administrators who will need full access to all data on the site (including data they themselves didn’t create), and granting that access is simple and straightforward with Full Control. But I cannot figure out how to prevent the admins from modifying the underlying lists. I’m trying to prevent a potential accidental list modification or deletion by a well-meaning but inexperienced admin…

Is this possible, or are these levels of permissions linked and inseparable?