I am working on a trip report to have all the deeds, but since you asked.... Once the plane lands, everyone is told to remain seated, our plane pulled up to the terminal and the relief crew was already waiting at the jet bridge. The old crew packs up and quickly exits, the whole swap process took about 30 minutes.
I do want to note what I find the most interesting is that this relief crew should only be working for 8-9 hours (because AC26 on the way back stop at ICN as well), I suspect AC want to prevent crew time-out in case the plane need to remain in Shanghai longer.

But yes that's entirely the intent. China's strict quarantine requirement made most NA airlines to do the crew stop in ICN (I suspect is because it cost less vs NRT/HND for landing fees?)