I want to update my iOS version

iPhone 8 and newer can be updated to iOS 16.

iPhone 6s and iPhone 7 can be updated to iOS 15.

iPhone 6 and earlier can be updated to iOS 12, or earlier.

Remove any add-on VPN, free up sufficient storage, remove any beta profile, force-restart, connect to Wi-Fi, and update.

Links…

Update iOS on iPhone - Apple Support

How to uninstall iOS or iPadOS beta software - Apple Support

Force restart iPhone - Apple Support

If the update fails, use a Mac or Windows PC to update.