Open Settings on your iPhone or iPad
Tap your name
Tap iCloud
Tap Manage Account Storage or Manage Storage
Review what is using space
Delete old iCloud backups
Turn off backup for apps you do not need
Delete photos and videos from iCloud Photos
Empty the Recently Deleted album in Photos
Delete large files from iCloud Drive
Remove unnecessary documents from apps using iCloud
Delete old Messages attachments stored in iCloud
Turn off Messages in iCloud if you do not need it
Delete Mail attachments and old emails if using iCloud Mail
Remove unused app data from iCloud
Check shared albums and delete unwanted items
Sign in to iCloud.com and remove files there if needed
Empty the Recently Deleted folder in iCloud Drive
Restart your device after clearing storage
Upgrade your iCloud storage plan if you still need more space