iOS 12.1.3 (build 16D5037a) is an official Apple over-the-air update for the iPhone 6s+, released on 2019-01-07T18:07:19Z. The update package is 70 MB. This is a delta (partial) update that requires 12.1.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: e6e0bf4eac4225f43342fa8940e35f61c9589b8a.zip.