How do I install v10 or v11 production with easy install script now that v12 is the default? [Question Revised for Clarity]

Currently there is no way to install v11 as you will be presented with v12 no matter what you do. So attempt to upgrade from v10 following steps provided in this post below:

You might encounter some issues. Resolve them and once you are able to launch the upgraded v11, make a backup and install a fresh v12 instance. Restore your created backup and you should be fine from here on. That’s the way i solved my latest attempt to migrate from v10 - v12.