iOS 12.0 (build 16A366) is an official Apple over-the-air update for the iPhone 6s, released on 2018-09-12T19:11:20Z. The update package is 1.73 GB. This is a delta (partial) update that requires 10.3.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 8689a2da15d1c9f64d1726745f8dd4f92af08a9b.zip.