Got accepted into Penn State and have questions?

I got into DUS and want to major in MechE. From what I understand you cant declare a major until your 4th semester (spring of sophomore year). On the PSU website I saw the MechE academic plan for courses to take, as a DUS student can I still follow that plan? Also does everyone declare their majors later? do people who are directly accepted into a school have an advantage or is it basically the same thing?

Yes, you still follow your recommended academic plan. Everyone declares an official major after sophomore year. There is no advantage.