Currently there are 15 native Telephoto Prime lenses for Canon R6 and 11 of these lenses are autofocus (AF) type.
R6 also has a sensor based image stabilization system which means that all of these lenses will be stabilized when used on R6.
Since Canon R6 has environmental sealings (Weather Sealing), you may like to couple your camera with one of these 11 Telephoto Prime lenses with Weather Sealings.