Device storage
I want to clear space on my device by deleting the photos on the device. Will I completely lose the pictures or videos if i delete them even if I use iCloud storage?
iPhone 7, iOS 14
Yes, deleting photos and videos from your iPhone will also delete them from iCloud Photos, if you are using iCloud Photos across your devices.
Transferring the data to your computer or an external drive would be an option to free up space in iCloud:
Archive or make copies of the information you store in iCloud - Apple Support
Manage your iCloud storage - Apple Support