How to transfer storage use
How do I switch my storage usage from my iPhone to the iCloud
Question marked as
Tap Settings > [your name] > iCloud > Photos. Tap Sync this iPhone. In iOS 15 or earlier, tap to turn on iCloud Photos. Select Optimize iPhone Storage to save space on your device.
Manage your photo and video storage - Apple Support (IN)
Enabling iCloud for Photos, Notes, Videos, Reminders, Messages, and more, as depicted in the provided picture, means that if you delete any or all data from one device, it will also be removed from iCloud and all other devices linked to the same Apple ID. Likewise, the reverse is true as well.