Finder is completely ignorant of the wildcard concept, and as you have been directed, you need to use the Terminal application to expose the modern UNIX operating system command-line and its wildcard support.
Apple's Spotlight does not allow literal (*) wildcards, but does permit implicit wildcarding based on how one uses the reserved, name keyword:
kind:pdf name:abc
will find every PDF whose filename has the string "abc" in it.
name:.pdf
will find every filename whose extension is pdf.
kind:pdf (name:out OR name:impose)
will find every PDF filename whose filename contains the case-insensitive strings of out or impose.
kind:pdf keyword:processed
Find any PDF that contains the case-insensitive keyword processed.
Apple has an article, Narrow your search results on Mac, that discusses using Spotlight key words.