Think of it this way. You beat multiple people to get the place.
Oxford chose you specifically over others that may have had a higher raw score in the PAT. They know what they’re doing and they know who they want. Take it as a compliment. 👍
The college will have transitional information for new students, thoughts for study skills and a reading list. And, some thoughts on how to use the reading list (don’t study it all..!). Might provide some fun stuff to do over the summer.
The tests are designed to be difficult and I’m sure there’s an element of luck in whether the questions are close to what someone may have seen before, or whether someone has to dig deep to get towards the answers. The test is to get you the interview, you obviously did exceptionally well in the interview to gain the place. Well done. You might have seen the physics admissions report, they’re aiming to have a mean of about 60 I think. You can see at your PAT score what proportion gained an offer (for physics anyway), you may have been very strong indeed at the interview.
Short answer, Oxford were well impressed with you. Enjoy the course!
(Parent of an offer holder, and myself an unsuccessful Physics applicant many many many years ago)