Per the Play Developer Console section on the store listing page you must, "Upload up to 8 Android Automotive OS screenshots. You must upload at least 2 portrait and 2 landscape screenshots. Screenshots must be PNG or JPEG, up to 8 MB each, 800 px by 1,280 px for portrait, and 1,024 px by 768 px for landscape" as part setting up the Android Automotive OS form factor.
Additionally, the developer guide states "Note: When taking Automotive OS screenshots for your store listing, make sure to use a generic system image. Your screenshots should not reference any Original Equipment Manufacturer (OEM) in particular."
As such, I've been able to take the landscape screenshots using the Automotive (1024p landscape) hardware profile available in Android Studio after downloading one of the generic emulator images. However, there isn't a suitable portrait hardware profile available and trying to create one using the New Hardware Profile button in the Virtual Device Configuration window doesn't seem to work.
Update
Original
To take portrait screenshots using this version of the emulator, I created the following hardware profile:
Then I created a virtual device using that hardware profile and the API 33 Android Automotive with Google APIs system image.
Sample screenshot:
Since the climate controls were overlapping, I used adb shell wm size 1200x1920
(1.5x the resolution) to change the resolution of the emulator (but the screenshots still are taken at 1280p)