With the Android Studio Chipmunk release 2021.2.1 it should be possible to create a resizable emulator as it is described here: https://developer.android.com/about/versions/12/12L/get#resizable-emulator.
But I am unsure how to create one. Where can I find the resizable device definition in the Device Manager? There is no such button, as you can see in my screenshot below. I also checked the Hardware Profile and the System Image section, but I could simply not find it.