watchOS 5.3 (build 16U6569) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2019-07-22T19:17:16Z. The update package is 169.29 MB. This is a delta (partial) update that requires 5.2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 1b91cadfeb5291dc9bf2339afed0731da2aa27dc.zip.