Back up your iPhone to iCloud or a computer
Open Apple’s Beta Software Program website and sign in with your Apple ID
Enroll your device in the iOS beta program
On your iPhone, open Settings
Tap General
Tap Software Update
Tap Beta Updates
Select the iOS 26 Beta option if available
Return to Software Update
Tap Download and Install
Enter your passcode if prompted
Keep your iPhone connected to Wi-Fi and power until the update finishes