I am wondering if there's a way to change my World Clock time to 24-hour format (I use UTC for meteorology/aviation), while keeping my phone local time in 12-hour format? I am also wondering if you can do this for the Apple Watch Series 6?
I do not see a way to do this and am hoping this could be added during an update.
The World clock uses the same settings as your regular clock. You can set the Watch to either 12 or 24 hour, but it does the same for both regular and World clocks. Requests for feature changes go to the feedback link, Feedback - iPhone - Apple
On your iPhone, tap on:
Watch > My Watch > Clock
and select 24-Hour Time. If I remember right, that should change you watch format without changing your iPhone format.
Using the Watch app allows for the whole watch to be in 24-hour format, not a specific world clock. I’m trying to get only one of my world clocks (UTC) to be 24-hour format and keep my local time (PST) in 12-hour format.
That is correct. But your original post said you wanted the watch in one format and the iPhone in another. What you are asking now is different and AFAIK cannot be done.