For those who didn’t notice it yet, you can change font color and size of your profile message by using special tags.
For colors, both color names and hex code can be inserted to determine the color. A full list of html color names can be found here. Size wise, using <size> along with a number would be sufficient.
Still, do be aware that character limit in profile message is very low, so chances are, you can’t have a full sentence in it. It’s still worth a try though, regardless.