Step 1 - Visit How to download macOS - Apple Support
Step 2 - Scroll to the section “use the App Store or your browser”
Step 3 - Click on the link for “Monterey 12” (or “Big Sur 11” If Monterey does not work)
Step 4 - The link will ask you to open in the App Store, and will take you to this page within the App Store:
Step 5 - Click “Get” and follow the steps to update your operating system.**NOTE: If you try to install Monterey and get a message that this update is not available, try Big Sur on Step 3.