iOS 12.1.3 (build 16D39) is an official Apple over-the-air update for the iPhone 6s, released on 2019-01-22T18:11:04Z. The update package is 322.89 MB. This is a delta (partial) update that requires 12.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 6566abb08ce9d2041a08dc691b76b5ce82b83ccb.zip.