Older versions of Pages cannot open documents created in newer versions. If you downgrade to Pages 6.0, you likely will not be able to open documents created in Pages 12. Always keep a backup of documents in the newer format before attempting a downgrade.
That usually means:
The most reliable way to get an older version is through your App Store history. Apple allows you to download the "last compatible version" of an app if you have owned it in the past. Open the . Click on your Name/Profile icon in the bottom left corner. Find Pages in your list of purchased apps. Click the Download (cloud icon) button. download older version of pages