I have many Word files, a few hundred, which I'd like to convert to PDF. Is there a way, free? Alternatively, I have the same files as RTF (long story). So maybe, I could convert from RTF to PDF...? I ...

You can convert Apple's HEIC files to PDF on a Mac or Windows computer using the free Convertio website.

To convert PDFs into Word files and on Mac, you should edit them with Google Docs or other third-party applications.