tone mapping is only needed/used when HDR is being transcoded.
if HDR is is being direct played, then there is no tone mapping required or used.
it is better to avoid transcoding HDR, see @ Plex, 4k, transcoding, and you, but if/when desired it can be done if you have sufficient and supported server hardware.
tone mapping helps prevent the ‘washed out’ colors that can happen when transcoding hdr to sdr.
