All you need to do is enroll your device into the Apple Beta Software program and install a config profile to get the iOS 16 beta on your device.
Once your device is backed up, it's time to sign up for the Apple Beta Software Program, which allows anyone to try out prereleased software for free, to provide feedback to Apple on quality, usability and issues.That will take you to another page, where Apple will lay out everything you need to do to download and install iOS 16 beta on your iPhone.
To download and install the iOS 16 beta on your device, you must now install a configuration profile on your iPhone. .
You may have concerns whether or not this is a privacy breach, but rest assured that this config profile simply allows Apple to deliver and manage the iOS 16 beta on your device.
You must first download a config profile from Apple's website before you can update to iOS 16 beta.Once your iPhone boots back up, go to Settings > General > Software Update, hit Download and Install and enter your passcode to begin the process of updating to iOS 16 beta.Once the config profile is downloaded and your phone reboots, you can download and install the iOS 16 public beta