You’ll see two separate window panes and you’ll want to click on the one with the name Video. Here you’ll find all the possible settings for your camera.
The first thing to check for is what camera is being used by the active Google Meet call. In this tutorial you see that C922 Pro Stream Webcam #3 is being used for this call. If you click on the arrow down icon next to the camera name you might see other devices listed. If your on a notebook you might see the name of the built-in camera. Select it and see if you get an image.
Are you joining the Google Meet video call with a USB webcam but can’t see it listed in the camera list? Then go ahead and unplug the webcam from your notebook and then plug it in again. Sometimes this has the effect that Google Meet recognizes the camera and activates it.