How can I get the Google Pixel 3 emulator in Android Studio?

Official AVDs for Pixel 3 and Pixel 3 XL are available since Android Studio 3.4

To add a notch in the emulator, choose any device with Android Pie system image (9.0). Build it, then go to Settings > System > expand 'Advanced' > Developer options > 'Drawing' section > 'Simulate a display with a cutout' on the emulator.

You can use it until they add the official skin

*NOTE: The 'Developer' option is not shown by default on Android phones. Please see the Android Documentation to learn out how to enable it.