Hmm. I could've sworn I had a Web Clipper app on my iPhone awhile back, but it disappeared around iOS 14...
Anyway, the process now seems to be to clip via the share sheet. In the process, Evernote asks for notebook and tags to associate the note with. I don't understand why Evernote cannot create a new tag, but can fetch the list of existing tags to choose from. Sounds like an API adjustment is needed.