The “Camera Boom” that they are using is a “Spring Arm” component you can add to your Blueprint.
If you attach the camera to the spring arm in the Viewport tab of the blueprint and make sure that the camera’s location and rotation are set to zero, than the camera will look down the spring arm and you can adjust the length of the spring arm to make it zoom in and out.
They have most likely changed the name of the spring arm to “Camera Boom”