Currently there are 17 native Standard Zoom lenses for Sony A6400 and 16 of these lenses are autofocus (AF) type.
Sony A6400 doesn't have a sensor based image stabilization system but 7 of these Standard 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 13 Standard Zoom lenses with Weather Sealings.