I was never very good at drawing, but evidence shows I did scribble a lot.
My son loved to draw, and is still pretty good but seems less interested since his early teens. He, too, spent long hours with his different dolls, in addition to the video games.
I'd say so the same things as for a girl, honestly. Provide opportunities to draw/paint/sculpt/make noise. They will do so. :)
I think it's more around school ages that things change more. And puberty, or course.