Apple iOS 12.3 Is Available Now on 3uTools
Apple has just released iOS 12.3 for its iPhone, along with several new version of the operating systems for iPads, Macs, Apple Watches, and Apple TVs. The updates are largely focused on the video services that Apple announced at its March 25 event—namely, a revamped Apple TV app, Apple TV Channels, and an expansion of AirPlay 2 to devices produced by Apple's partners.
If you want to upgrade to this version:
Step 1 Connect your iDevice to PC with a USB cable and launch 3uTools.
Step 2 Navigate to Flash & JB → Easy Flash and select iOS 12.3. After you click Flash, there will be a popup reminder and please read it with caution. If you want to save your data, please check the box "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 restored to iOS 12.3 after reboot.