Want to downgrade from Monterey back to Sierra
iPad 2, iOS 9
The computer can only downgrade to the version this computer Originally came Installed with As New.
If this computer came new with Big Sur macOS 11 - that is the oldest version this computer could be downgraded to.
The Apple Licence of Use Agreement prohibits doing otherwise.
You can revert to the closest available version of macOS that shipped with your Intel-based Mac with macOS Recovery, but you won't be able to keep the data on your Mac.
Shut down your Mac, then hold Shift+Option+Command+R while your Mac is restarting. Erase your hard disk, then install macOS over the internet. If your drive is formatted as APFS, you might have issues erasing the disk with macOS Sierra or earlier.
Use macOS Recovery on an Intel-based Mac - Apple Support
File system formats available in Disk Utility on Mac - Apple Support
Downgrade from Monterey to Sierra
