How can I convert old MacWrite file to Microsoft Word on MacBook Pro Ventura 13.7.5 (22H527)

I haven't tried it recently but I think LibreOffice still will open and read MacWrite files. You can download LibreOffice from https://www.libreoffice.org/ and install and use it with no fee. Open the Writer app in LibreOffice and then use its File - Open menu item to open the MacWrite file and then save the file in Microsoft Word format (.docx).

The latest LibreOffice 25.2.2.2 opens my old suffix-less MacWrite 4.5 document with images from 1990, and saves it as .docx OK.