FIRST LOOK ANDROID Q BETA 1 ON GOOGLE PIXEL 3 XL ( No difference between android 9)
Get Android Q beta 1 for all google pixel : https://developer.android.com/preview/download-ota
To install an OTA package to a device:
Download an OTA device image from the table below.
Reboot the device into Recovery mode.
On the device, select ADB sideload.
Connect the device to a computer with the Android development environment loaded and the Android Debug Bridge (adb) tool installed.
Run the following command: adb sideload (ota-pack)