iPhone Storage Vs iCloud Storage

When you get a popup message on your iPhone or iPad that the storage is full.

Look closely at the storage of the iPhone and iCloud

iPhone Storage (Setting > General > iPhone Storage)

1. Total storage remains the same throughout the life span of the iPhone
2. Storage can not be increased
3. You may take a backup on Mac or PC using iTunes / Finder

iCloud Storage (Settings > [Tap your name] > iCloud)

1. By default, every user gets 5GB of free storage space
2. You can buy more storage based on your requirement 50GB, 200GB, or 2TB with a monthly subscription to Apple One you may get more storage.
3. Based on your storage capacity you can back up your iPhone or iPad

The iCloud storage space can be shared between your family members