Currently there are 11 native Telephoto Zoom lenses for Sony A6400 and 10 of these lenses are autofocus (AF) type.
Sony A6400 doesn't have a sensor based image stabilization system but 8 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 9 Telephoto Zoom lenses with Weather Sealings.