The OP’s understanding is correct - you must get into Kelley to major in accounting at IU. Almost all Kelley classes are somewhat challenging. However, it’s doable to get very good grades if you are willing to work hard.
I had good grades in high school, but I didn’t work particularly hard to get them either. I often wouldn’t study much/at all for tests because it wasn’t necessary. In Kelley, I typically dedicate 2-5 hours the night before an exam to study, depending on the class. It would probably be better to study further in advance, but that system works for me.
Note that you now need a 3.5 GPA in addition to not getting any grades below a B for automatic admission:
https://kelley.iu.edu/Ugrad/Admissions/CurrentIU/page39067.html
This is probably doable if you work hard, but will be challenging especially if you are going to rush. One of my best friend’s roommate rushed last year and was sometimes up until 3 or 4 in the morning doing rush stuff.
I can help you plan a schedule that gives you the easiest path to getting a 3.5 and nothing below a B, but it will still be challenging. Just let me know if you are coming in with any credits, what your academic strengths/weaknesses are, and if you’ve taken any classes in high school such as stats, accounting, Excel/Access courses, or econ that might help you in college. You don’t need any of those classes coming in, but some knowledge would make the intro classes easier.