you can use "directo/a", as the type of boldness that's straightforward. "(palabras) directas". ser directo means the person doesn't beat around the bush.
Implying a certain level of bad education: "descarado/a"
If it's bold meaning brave, or shameless, "atrevido/a" (audaz is a little more poetic, maybe)
Crudeness "crudo/con crudeza