We support a few options for styling subtitles/captions today.
We have limited styling options for subtitles today.
You can add:
You cannot change font type, color, and size.
Note that SRT subtitles don't support styling.
Typically the best way to have granular formatting of subtitles and captions is via your video editing application. For example we support export of FCPX Titles which you style in FCPX.