When you get a popup message on your iPhone or iPad that the storage is full.
Look closely storage of iPhone and iCloud.
iCloud storage is primarily for keeping a copy of your iPhone data safely on the cloud. If you delete data on iPhone, data on iCloud is gone too.
Turn iCloud features on or off
- On your iPhone, iPad or iPod touch, go to Settings > [your name] > iCloud.
- Turn iCloud features on or off.
Turn iCloud features on or off - Apple Support
iPhone Storage (Setting > General > iPhone Storage)
- Total storage remains the same throughout the life span of the iPhone
- Storage can not be enhanced
- You may take back up on Mac or PC using iTunes without iCloud
iCloud Storage (Settings > [Tap your name] > iCloud)
- By default, every user gets 5GB of free storage space
- You can buy more storage based on your requirement of 50, 200GB, 2TB with a monthly subscription
- Based on your storage capacity you can back up iPhone or iPad
- Space can be shared between your family members for a storage plan beyond 200GB