Flight aware app or website. You then put in the airport (like ZhengZhou to Anchorage in the route choices and usually you can find UPS planes. this year I could only find my exact plane as it left Korea. It was UPS99 which they seem to be using for some of the runs from Korea to Anchorage and then Louisville at which they have another plane (in Korea???) that gets labeled UPS99 and it continues. There are also other UPS flights as well from Korea on but I cannot figure out what comes from China. You look for the actual departure date/time from the location and then try to match it to flights that have departed. That is how I snagged UPS99 from tracking data to the flight data on Flight aware. Flighaware is available as iOS/iPadOS app, or you can use for free a basic non login account on their web site (I usually have both going LOL).
Website:
https://flightaware.com/
Here is what you will see (I like the website layout a bit better than app):
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Next enter your departure and destination airports I put in the Incheon origin and it gives several choices and Anchorage in destination which is first part of US leg.
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And then click on the blue search icon at right of these two and you see this with all planes left and scheduled to leave Incheon Korea.
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At this leg of Journey (I could not find matching plane times from ZhengZhou China so clueless on what plane it leaves on) you can likely assume with our batches this group UPS planes so go to the left of this and choose the refine flight results and choose airline turn off all and then select UPS and you then see this:
View attachment 1853086
Note that for today UPS99 has left similar time to when it left yesterday with my phone now out for delivery. They switch actual planes as the other plane is likely still in US but heading back to get in the chain of iphones and whatever else is coming out of Korea from China. That is why others gave you the link for the UPS 99 that just left Korea if your departure from Korea matches the time then they have already found you the plane to follow. you can then follow your tracking. When it gets to Anchorage about hour after arrival your tracking will show. Same when it leaves for Louisville.
Hope that helps. Now some years and maybe with China other cargo haulers and airlines are used for part of the journey to Korea (or Taiwan) to Anchorage. At that point UPS picks up if not before.