Yep, you can do that now without hacks or employing the somewhat awkward combination pseudo-elements and counters. Your best bet? The ::marker pseudo-element. We just updated the Almanac entry on that for your reference pleasure.
ul li::marker { font-size: 150%; font-weight: bold; color: lightgreen; }
You can also control the text of the marker itself, meaning you can swap out bullets for emoji, or numbers for custom counters. Manuel Matuzović made note of this week that it was just a few years ago this was much more difficult. Go CSS!
Support is pretty darn good and it’s been around for a little while but I always tend to forget about :marker so this is a good reminder to use it more often.