Currently there are 9 native Telephoto Prime lenses for Fujifilm X-T2 and 3 of these lenses are autofocus (AF) type.
Fujifilm X-T2 doesn't have a sensor based image stabilization system but 1 of these Telephoto Prime lenses features optical image stabilization.
Since Fujifilm X-T2 has environmental sealings (Weather Sealing), you may like to couple your camera with one of these 3 Telephoto Prime lenses with Weather Sealings.