.. font, font size and colour are all configurable simply by editing the .ASS header. I think a few replies after my post, the OP had edited the default V4+ Style (global) and then run with normal settings in Events.
Colour 808080 turns the font dark grey on my LG C8 - perfect for dark room cinema and exactly what this part of the thread was about.
I agree the configuration options in ffmpeg are very limited - and ideally Emby should give us these options but as this appears to be the ONLY way to get colours working via the LG App then a quick script is all that is needed to convert the existing internal or external SRT subtitles to .ass and simply set them as default using the .forced. in the HDR only filename.
Edited by rbjtech, 15 April 2019 - 05:12 PM.