The sources that I have seen for VideoDecompressionSession use H.264 as the example decoder. I suspect that H.265 could also be decoded with VideoDecompressionSession. Can anyone confirm that?
VideoDecompressionSession for H.265 (hevc)
VTDecompressionSession can decode a large number of formats, including HEVC. You can also list the available decoders to be sure what are the supported format on a particular device.