It is possible that you could receive a new offer from the University of Sydney (USYD) if you have already accepted an offer and have changed your preferences on the Universities Admissions Centre (UAC) to include another course from USYD as your first preference. However, whether or not you will receive a new offer will depend on the availability of places in the course and whether you meet the entry requirements.
If you would like to inquire about the possibility of receiving a new offer for a different course at USYD, you can contact the university's admissions office. They should be able to provide you with more information about the admissions process and whether it is possible for you to receive a new offer.
Keep in mind that if you do receive a new offer and decide to accept it, you will need to withdraw your acceptance of the original offer in order to accept the new one. This can usually be done through the UAC website or by contacting the university directly. It is important to carefully consider your options before making a decision, as withdrawing an acceptance can have consequences such as the loss of any fees paid or the loss of a place in a course.