Here is a directory of sample files from the IPTC with pretty much every field filled out:
https://iptc.org/std/photometadata/examples/Open this image in Photo Mechanic and then open its Metadata Info panel and I think this will essentially be what you are looking for
I've also attached our sample file with all of the fields filled out with our field names, so if you upload this image to somewhere else that displays its metadata, you'll see what Photo Mechanic calls that field.