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 backups you no longer need
Turn off iCloud backup for apps you do not want backed up
Delete large files from iCloud Drive
Remove unnecessary photos and videos from iCloud Photos
Empty the Recently Deleted album in Photos
Delete old messages and attachments in Messages
Remove unused apps that store data in iCloud
Check Mail attachments and delete large emails if needed
Optimize photo storage on your device
Upgrade your iCloud storage plan if needed