If you had Pages/Numbers/Keynote installed prior to the upgrade to Catalina, you might be able to get the latest compatible version for Catalina.
Launch the Mac App Store with the same Apple ID as you used to obtain these applications previously. Press cmd+0 (zero) to open the Purchased panel. First, locate Pages and select the Update or cloud symbol (whichever is present). You will initially receive a dialog that you need a newer version of macOS, and after clicking OK, another dialog may appear offering to install the last compatible version of Pages for Catalina (v11.1). If this works, repeat it for Numbers and Keynote.
If the second paragraph does not work, there will be no means to get Pages v10.2 - v11.1 for Catalina, and you will need to use Pages for iCloud, or compatible Pages for your iOS/iPadOS installation.