The minimum requirement is actually iOS '''13.0''' (thirteen.zero) The only way you may be able to install a older version is if you had a older version installed on your Apple ID account in the past and is in your Purchase History (yes both free and paid for apps are listed there). in Settings > Account Name > iTunes & App Store > Apple ID link > View Apple ID > scroll down to Purchase History. btw there is a iOS 12.5.'''6''' update that has a vital security patch. Installed the update on my old iPad mini 2. It is said you can downgrade to 12.5.5 if you have issues though I have not had any issues on my iPad mini 2 so far.