You can go to your settings to install iOS 18 beta if your device is running iOS 16.4 and used with an Apple ID enrolled in the Apple Developer Program:
- Go to your iPhone Settings
- tap on general
- He chooses system update
- go to Beta updates
- Select the iOS 18 developer Beta
If you don’t see this option, go to settings, He chooses Privacy & protection, And empowerment Developer mode.