If there is a flight plan filed, you do NOT have to ask the aircraft for their intentions, as you know them. All the aircraft has to do is Check In with you, nothing more. It is silly for a airliner on an IFR flight plan to have to ask for flight following to X destination.
It’s also good to point out, that if you are departing, and tower just gives you “frequency changed approved” and does not send you to approach or departure, you do not needed to switch to those frequencies when not asked to :)