Celebrate with your swimmer!
Distance events can be intimidating and every race is worth celebrating. Allow the coach to talk to your swimmer about what was done right, and what might need some correction.
As the parent or teammate, your job is to point out the positives.
Be a safe soul for the athlete to unload and release all of one's feelings.
Always follow up with a good snack or post-meet meal. Distance swimmers are going to be hungry after the events are finished.
Transition to the next event too.
Generally, swim meets end with team relays. Star swimmers might be expected to be in relays that follow the distance event.