Maybe, but the more common thing to happen is they make a hole and use an oversized eschution plate to cover it up. If the plumbing backs up to a closet, or some other place where they can access the plumbing (a closet maybe?), they MIGHT be able to make a smaller hole. Note, if you are changing the fixture, unless you are fixing it, you normally would be required to update it to the current code which means use of either a pressure balanced or thermostatic controlled shower valve. These prevent the potential scalding that may occur from a change in water pressure that takes away the cold in the mix.