Do you mean the title of the episode is in the file name?
Or do you mean that the title is embedded as a meta tag? In the latter case, Plex can read it already without any involvement of .nfo files or other things.
For the former case, there is 3rd-party software which can take the file name and extract a portion of it and write it as meta tag into your files.
I’ve answered you the same question already a while ago: Is there a program/batch process that automatically creates nfo files based on the filename? - #7 by OttoKerner
