Apple does not provide direct user downloads of past full installers of Pages, Numbers, or Keynote.
If you previously installed those applications, they should be in the Purchased section of the Mac App Store application, provided you launch it and sign in with the same Apple ID used to previously install them. For Mojave and later, one presses cmd+0 (zero) to display that Purchased panel.
On the Purchased panel, and using Catalina as an example, one should see these applications with an Update button. Because currently, these applications now require Big Sur or later, a dialog will appear indicating one should upgrade their operating system. Acknowledge that dialog, but do not click Cancel. A secondary dialog should then appear asking if you want to install the latest version of the application for macOS Catalina. You acknowledge that and v11.1 of the applications is installed.
This does not pertain to iWork '09 applications.