Delete unused apps
Offload unused apps
Clear Safari history and website data
Remove large message attachments
Delete old photos and videos
Empty the Recently Deleted album
Review and delete downloaded files
Remove offline music, podcasts, and videos
Clear app caches where available
Restart your iPhone
Update iOS
Check iPhone Storage in Settings
Use iCloud Photos or other cloud backup
Delete duplicate files and screenshots
Remove old mail attachments
Reset and restore only if necessary