The ability to sort or filter by words contained in the filename would be quite useful, especially in troubleshooting problematic files from particular sources. (ie RARBG files don’t match properly). I don’t think a dropdown would be necessary for this feature, just a text field.
There’s already some suggestions covering what you describe. Please comment/vote in those threads to help us avoid distracting or cannibalizing votes.
https://forums.plex.tv/t/search-by-filename/316293
Unless I’m missing some unique aspect of your suggestion, I’ll close this thread as a duplicate.