In Windows 10 Creators Update, the Mini View feature is introduced:

I'm particularly interested in this feature, but I don't know how to get it to work. For example, in Groove music, I don't see an option for switching to mini view.
So, how do I use this feature?
Attribution: Image appears to be copied from
https://winblogs.azureedge.net/win/2017/04/Mini-View.jpg