Currently there are 18 native Telephoto Zoom lenses for Sony A6400 and 17 of these lenses are autofocus (AF) type.
Sony A6400 doesn't have a sensor based image stabilization system but 13 of these Telephoto Zoom lenses features optical image stabilization.
Since Sony A6400 has environmental sealings (Weather Sealing), you may like to couple your camera with one of these 16 Telephoto Zoom lenses with Weather Sealings.