Apple is the gift that just needs to keep on giving. A day after iOS 12.1 release, Apple seeds the first beta of iOS 12.1.1, you can click here to know what's new in iOS 12.1.1. Now, it is available on 3uTools.

As always, please back up your device before flashing. 

Step 1 Connect your iDevice to PC with USB cable and launch 3uTools. 

Step 2 Navigate to Flash & JB → Easy Flash, and select the firmware iOS 12.1.1beta. There will be a popup after you click Flash, please read it carefully. If you want to save your data, please click the checkbox "Retain User's Data While Flashing". 

Step 3 Keep a good connection and internet while flashing, wait patiently for around 5 to 10 minutes. Your device will be upgraded to iOS 12.1.1 beta 1 after reboot.