This picture is very small and actually part of an art style I rarely use. I call it mini-chibi. It’s a typical chibi style drawing, but smaller. I draw it at a size where the head starts as the size of a dime.
So yes, that picture is actual size. If not a bit bigger, actually. Hm. I’ll have to compare to be sure. But there is an uncoloured version of her (and the other characters from HPH) if you click the small Adrienne.