I needed a croped section of a RTSP live stream from a UniFi Protect camera, since I am filming my yard from a shed and wanted to see a cutout of the front door from my 4K camera.
This article will show you how to enable the RTSP live stream on the UniFi Protect camera, how to setup a streaming server and how to actually execute the processing of the live stream.
The following screenshots are made from UniFi Protect application on version 2.7.18