Up until a few months ago there were a lot more options for styling your app store description. If you wrote that before the change you can keep it until you update the description.
No unfortunately you can't. Apple are fair in this manner where they don't allow for flare in terms of appearance.
My best advice is get creative with your wording!
In that sense, I'm glad apple are balancing the scales between arty people and non arty people which both produce different kinds of apps but both of the same quality.