Op,
As for requesting a gap year, some colleges like H and Y encourage it and admitted students receive a letter talking about it and the deadlines soon after they get their admissions acceptance letter. I presume that penn is the same way since you already know what is the deadline for gap year notification. Your DS could call admissions or email them. He says that he is considering a gap yr and wants to find out what is involved in terms of deadlines etc. For instance, does he have to tell them by 6/3? Could he decide in July and still take a gap, etc. It’s better for him to contact them ASAP so that if the deadlines are firm, he can start looking into options. Takes a while to plan a gap yr. Dont worry, penn won’t take offense. It adds maturity and diversity to the class.