iOS 12.3 (build 16F5139e) is an official Apple over-the-air update for the iPhone 6, released on 2019-04-22T17:08:58Z. The update package is 402.85 MB. This is a delta (partial) update that requires 12.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 9f3b678795c477c394c463f9fd2db8c8462478c3.zip.