That Microsoft July 13 date has no bearing on your existing Office documents, but may disable Office 2019.
If you have never previously installed Pages, Numbers (or Keynote) from the Mac App Store, then you cannot get v11.1 of these applications for macOS Catalina now, as the current applications require macOS 15.7 or later.
In case you may have forgotten whether you previously installed these applications, launch the Mac App Store, sign-in with your Apple ID, and press cmd+0 (zero) to open the Purchased panel. If Pages and Numbers do appear, then you can click their Download symbolism and a dialog asking you if you want to install the last compatible versions for macOS Catalina will eventually appear. If Pages or Numbers are not on this Purchased panel, you are done. Note that Pages, Numbers, or Keynote are not Microsoft clones and may treat your documents differently than Microsoft applications.
The free LibreOffice Suite is a clone of Microsoft Office, so your existing Word and Excel documents will open allowing you to edit and save them. You want to download and install the Intel version of LibreOffice, and supporting user documentation is available.