iPadOS 12.1.3 (build 16D5037a) is an official Apple over-the-air update for the iPad Pro 12.9-inch (Cellular), released on 2019-01-07T18:06:41Z. The update package is 225.67 MB. This is a delta (partial) update that requires 12.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 534735a900a618e4c2efca2a81e90c16377d5d21.zip.