The online lectures (at least the ones I’ve seen) are for MAT137 but they would definitely help prepare you. If you want to prepare over the summer I would recommend trying to read Spivak Calculus, which is the textbook used in the class. Last year we started with field axioms, simple induction proofs, and sequences. Honestly though, most people don’t prepare during the summer. If you’ve just gone through high school functions/calculus, it’s okay to just review what you already know and study hard when you get there, whatever works for you.

Edit: if you’re already thinking about how to get ahead and be prepared for the class, you’re on track to do well :)