See, for example:
https://www.msofficeforums.com/word-...tml#post125011
The code there doesn't do the font changes & pdf creation you want, but it does show how to loop through all files in a nested series of folders.
It's also not clear from your post whether you want a single PDF for all files in the folder, or a separate PDF for each file: the latter is easy; the former could get complicated if different page layouts have been used.