I can't say that hands grow with exercise - that they become bigger or longer. However, doing finger exercises can improve the dexterity and flexibility of your fingers. It can also help stretch your fingers (especially with octave exercises)so you can reach far notes. But of course the stretch is limited to just how far your fingers can go. If you have small hands and you play piano, don't worry too much on not being able to reach very far notes. But with regular finger exercises your fingers can become flexible and fast so you can play far notes like how you play grace notes. You don't need to press down 2 far notes together if they are really far from each other. But you can them like grace notes.
If you need exercises or lessons on improving the flexibility and dexterity of your fingers try the Hanon book exercises. If you need courses on improving your hands' and fingers' flexibility and coordination, check out the Hand Coordination, Runs and Fillers http://www.pianomother.com/Hand-Coordination-Piano-Runs-Fillers.html