iOS 12.1.3 (build 16D39) is an official Apple over-the-air update for the iPhone 6s, released on 2019-01-22T18:10:55Z. The update package is 1.33 GB. This is a delta (partial) update that requires 11.2.5 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 60d4113ca2d72ecb260bbb6cfbb2417190e29e4b.zip.