Do I need to increase my iCloud Storage or System Storage?
I am not sure if I need to increase my storage or if I need to clean my phone from duplicate items, old messages.
[Re-Titled by Moderator]
iPhone 15 Plus, iOS 18
Let's first differentiate what iCloud Storage and System Storage is. iCloud Storage holds iCloud backups and sync data across devices, with the only exception of iCloud Photos data. System Storage holds the rest of your data including messages, emails, apps.
If you are full on iCloud Storage, that can be easily increased for an incremental price increase. If you are full on System Storage, there is a more tedious route you must take which is deleting any data you don't need or upgrade your iPhone with more storage.
What's the difference between device storage and iCloud storage? - Apple Support