Hi.
if it should automatically trigger.
Make a trigger larger than the door and a collider on the door itself.
then set trigger 2D event on trigger stay.
and set a transition, when triggered you can disable the collider (and play some animation)
then set another trigger 2D event with a trigger exit and a transition to the next state.
there you can enable the door collider back and then transition back to the state with the trigger 2D event on trigger stay.