iOS 12.3 (build 16F5129d) is an official Apple over-the-air update for the iPhone 6s+, released on 2019-04-08T17:05:13Z. The update package is 311.41 MB. This is a delta (partial) update that requires 12.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 0c1795cffc51cac4b7c1439d098f8c3c46577500.zip.