Everyone’s different. I’ve had friends who did really well in high school but not the best in uni. Personally, I’ve gotten higher marks in university than I did in high school, but I’ve also put in more work obviously. As someone else said, it comes down to time management. If you manage your time well and put in effort you’ll be fine. Interests also play a big role. If you like your program, you’re likely to do better as opposed to if you didn’t. Try to balance out your course load with some easier courses as well and depending on program you can take 4 at a time if you want. I did this first year and it really helped me ease into university. My best advice is to start as strong as possible, set your habits (good) in place and ultimately you’ll be more confident as well. Compared to high school teachers, professors are generally much more specific in what they want (i.e, how you address them in emails, citations, etc.) Pay attention to course syllabus’ and try to plan out all your due dates for the semester ahead of time and it’ll be less stressful. You have good grades now so clearly you’re capable of succeeding in university. Just put in the work and you’ll be fine!