iOS 12.1.3 (build 16D39) is an official Apple over-the-air update for the iPhone 6s+, released on 2019-01-22T18:11:24Z. The update package is 1.45 GB. This is a delta (partial) update that requires 11.0.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 5b3c0ae77c3401aab969cd77ec87bca912644f55.zip.