It depends on the restaurant or CS. The beverage on the dining plans is typically fountain drinks such as soda, coffee, tea, regular iced tea or lemonade. Specialty non-alcoholic beverages may or may not be included. It really depends on the venue so if something looks interesting you can ask, but if the price point is considerably more than the fountain drinks and/or if it's a non-Disney venue it's less likely to be included. You may have to use a snack credit instead if that's allowed.