Photos
Deleting iPhone photos safely so that there's still a copy saved
iPhone 7, iOS 15
When you delete a photo in Photos it will be saved for 30 days in the Recently Deleted album, where you can recover it from, if you change your mind later and want it back. So do not empty the Recently Deleted album, unless you are very sure that you want to delete the photos permanently.
There is one exception - if your Mac is syncing with Cloud Photos and you have used up all iCloud Storage, deleted photos will not be saved in Recently Deleted, but instantly deleted permanently, to help you free your Cloud storage quickly.