iOS 12.0 (build 16A5357b) is an official Apple over-the-air update for the iPhone 6s, released on 2018-08-15T17:07:02Z. The update package is 159.13 MB. This is a delta (partial) update that requires 12.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: bf76317fe3fe0fd02a92578a688812f9f358b8ab.zip.