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.
I just upgraded everything this morning (2022-07-13), and now "Resizable" is an option in the "Choose a device definition" page of Android Device Manager.
"everything": Android Emulator 31.2.10 would seem to be the relevant update.
Note that on the next page you can only select Sv2 or API 33 as system images.