Best way to encode down from H.265 Main 10 (10 bit).

[nicktheone]

I have a couple of files encoded like in the title and I'd like them to be in a more digestible format like plain H.265 or either H.264 since those are what my Plex server likes the most. I believe the use of Handbrake is in order in this case but I'm lost with all the dials and levers and I'd like to preserve the quality of the video if it's possible.

Anybody knows what I should do?

[ProWo]

Use my clever Ffmpeg-GUI to recode it to h264, crf 18-20, 8 bit.