This is difficult because FFmpeg does not automatically output the same format metadata as the input file, so we need to detect and add a lot of flags like:

-pix_fmt yuv420p10le 
-x265-params colorprim=bt2020:transfer=smpte2084:colormatrix=bt2020nc:range=limited:master-display="G(13250,34500)B(7500,3000)R(34000,16000)WP(15635,16450)L(10000000,50)"
-bsf:v hevc_metadata=colour_primaries=9:transfer_characteristics=16:matrix_coefficients=9

and that is just for HDR, not even Dolby Vision yet.
I hope FFmpeg make it more simple but there is a big arguing thread that makes it seem like they won't do it https://trac.ffmpeg.org/ticket/7037 :(

I also started a Q&A at this link https://superuser.com/questions/1835560/how-can-i-transcode-a-dolby-vision-video

This could be resurrected if FFmpeg supports it in the future

Just had a look at that Q&A and there was a reply today saying it is supported since FFmpeg 7.1

Since FFmpeg 7.1, it's as easy as adding parameter -dolbyvision 1

I don't know if this applies to subtitles or preserves the right metadata though.

Yeah that's amazing timing haha, maybe someone was following this issue. I'll reopen it

Unfortunately there is a bug in FFmpeg that causes it not to add the correct metadata in MPEG-TS files. I confirmed it using FFmpeg and MediaInfo so it's not something to do with UMS. But tsMuxeR can take that stream and produce the correct metadata still.