.docx became the 'norm' when Microsoft Office 2007 was introduced to the market a decade and a half ago. So I can't see how .doc could now be regarded as being 'more widely used'. (Only Microsoft use .docx as its default format though. Almost everyone else uses .odt).
Your problem isn't really with the file format(s) being used by people who send you files. It's more to do with the fact that you're using out-of-date software. While OpenOffice can read .docx files, it can't write them. However LibreOffice, which has been developed from OpenOffice and is compatible with macOS, provides a more up-to-date solution.
So switch to LibreOffice (which, as it's basically OpenOffice anyway, will look reassuringly familiar to you) and your problems will be over:
https://www.libreoffice.org/get-help/install-howto/macos/
Just like OpenOfficer Writer, LibreOffice Writer uses the .odt format as its default setting when you click on 'Save'. You can easily change it to .docx though:
https://www.howtogeek.com/281166/how-to-change-the-default-file-format-in-libreoffice/