In English, I may ask, "do you have tea?" to a waiter or waitress. This "you" may be plural since asking, "do you all (y'all) have tea?" makes sense, but I guess it could also be singular (more along the lines of asking if the waiter has the ability to bring tea).
In Spanish, I can think of a few options, but don't know what's best:
- ¿Tienes té?
- ¿Tiene (usted) té?
- ¿Tiene (el restaurante) té?
- ¿Tienen té?