iOS 12.1.3 (build 16D39) is an official Apple over-the-air update for the iPhone 6s+, released on 2019-01-22T18:11:43Z. The update package is 217.94 MB. This is a delta (partial) update that requires 12.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: d8bf4a8d6c92c5ca3c413c6d3dc24977494bcf49.zip.