Currently there are 24 native Telephoto Zoom lenses for Panasonic GH6 and all of these lenses are autofocus (AF) type.
GH6 also has a sensor based image stabilization system which means that all of these lenses will be stabilized when used on GH6.
Since Panasonic GH6 has environmental sealings (Weather Sealing), you may like to couple your camera with one of these 15 Telephoto Zoom lenses with Weather Sealings.