You can definitely leave early.
They have teamwork based activities that get you comfortable with getting to know new people whilst also taking you around some parts of the campus but mainly Building 11. There was a free lunch, speed friending (You will find super awkward people here or some super cool ones), they had a few society/club stalls set-up which were relevant to FEIT so you could get some info and possibly join them. They had industry talks (I had past students in mine, talked about their experiences at UTS and where they are now) and then a trivia (Personally did not enjoy it, I left early at this point along with more than half of the people in the session lol)
I recommend staying for the first few hours and then feel free to leave before trivia as the day begins to drag on from there. Have fun!