There are a few ways to check if your photos are on your iPhone or iCloud:
-Open the Settings app and tap your name at the top.
-Tap "iCloud." If you see "Optimize Storage" or "Download and Keep Originals" under the Photos section, your photos are stored in iCloud.
-Open the Photos app. If you see "All Photos" or "My Photo Stream" under the Albums tab, your photos are stored in iCloud.
-Check your iPhone's storage. Go to Settings > General > iPhone Storage. If the "Photos" section shows a number next to "Total," your photos are stored on your iPhone.