Apple is moving along through the beta phase of releasing iOS 12. The first version was released back in June, and today sees the debut of iOS 12 beta 6, and later the public beta. Typically the accompanying public beta release comes soon after and is versioned a release behind but is otherwise the same, thus iOS 12 public beta 5 equals to iOS 12 developer beta 6. 

Now beta 6 is available for iPhone and iPad on 3uTools. Before you go ahead and download iOS 12 beta 6, you are recommended to back up your device in case of data loss.

Operations

Step 1 Connect your device to PC with USB cable, then launch 3uTools. 

Step 2 Navigate to Flash & JB → Easy Flash, select the iOS 12.0beta6 firmware. If you want to save data, please click the checkbox “Retain User’s Data While Flashing”. Click “Flash” to start downloading iOS 12 beta 6 firmware.

Step 3 Please do not disconnect your iDevice and wait patiently until the process is finished, it would probably take 5 to 10 minutes. And after that, your device will be restored to iOS 12 beta 6.