Firefox itself doesn't have any way to view a Word or OpenOffice document in its native format. However, you can use a site like Microsoft Word online or Google Docs to generate a PDF. Probably you have a Microsoft account or Google account, or both.

I think the first step would be to save the document on Microsoft OneDrive or Google Drive, and then try to view/preview/edit the document (maybe through a right-click context menu on the file listing).

You might get a PDF preview immediately or you might get a full editing experience and need to call up a File > Print command using a menu in the page. (Firefox's print feature may pick up parts of the page that aren't part of the document, so that probably wouldn't give the best results.)

Can you find a way to do it?

This helped me convert ----> https://www.pdfforge.org

Thank you for your help.

Silly me, Libre Office has a command to export as PDF: File/Export As/Export As PDF.