The various tomes and manuals require Wish or Miracle to create them. Basically, they can be thought of as a whole bunch of wish scrolls put in an easier to use form.
Since I see no reason that a Wish couldn't increase a dragon's attributes, I see no reason that a manual or tome could not achieve the same results.
Assuming they haven't already used such means to boost their attributes, the only things that would prevent this are greed or arrogance. Fortunately, many dragons have an excess of both those personality traits.