iOS 15 has a neat feature called App Privacy Report, which allows the OS to record when apps use your microphone, location data, camera, and so on. Once a week you’ll receive a report of this data, which will allow you to check if apps have been accessing your data when they don’t need to. It’s a nice way to keep an eye on whether apps are violating your privacy.
To enable this, go to Settings > Privacy > Record App Activity and enable Record App Activity. However, the full version of the feature won’t be available right away.