searching on presence of a term prefix

Hey all, I'm wondering if there's a way to search for documents
based on whether a prefix was used or not, regardless of the
text indexed with that prefix.

I'm already indexing email attachment filenames with the "XFN"
prefix.  However, I may want to construct a query that returns
emails with any attachment filename in them at all.

Would I have to add a new boolean term to search against to
accomplish this?

Using XS Search::Xapian on Debian buster and bullseye.

Thanks.