Usually Freshman schedules are made by their advsior or academac advisment center. Some colleges accept AP credits based on the score you got and will give you that credit for that class. If you are undecided you have until your end of your sophomore to declare your major.
You don’t do anything regarding course selection when applying to the school.
After you are admitted and choose to enroll, the school will look at your AP scores, CLEP scores, dual enrollments, transfer credits, etc., and tell you for which courses you have been given credit and/or advanced placement.
A “typical” university will have defined plans of study for each major, and a “typical” freshman course schedule based on school/major. This “typical” can vary widely - Purdue engineering admits students directly to First Year Engineering which has a very well defined set of first year courses. LACs seem to be much looser, from my reading, with categories of courses and suggestions.
Either way, you will usually be assigned an advisor who will help review course selection, credit, placement, etc., and get you to a first semester schedule, after which you will register for classes (specific days/times/instructors). At Purdue, students get a specific time-slot to register and classes fill up quickly. Students may need to shift specific class dates/times to avoid overlap or even change courses (my D took 2nd semester Chem as 1st semester Physics was full).
This is all completed weeks before the semester starts and is repeated every semester.
That’s a “general” approach as I’ve seen it - I’m sure there are schools that vary.
Colleges (or arts and sciences divisions) where most or all students enter undeclared (and theoretically could major in anything) give students a lot of choice on the first semester courses, but also expect them to become informed about what they should choose to prepare for the majors that they may be interested in. There may be various levels of advising assistance, depending on the college.
If you know what your major might be, check the web pages for that department at the websites of the colleges and universities on your list. Usually there is a list of requirements for the degree, and often there is a suggested plan of studies that your advisor will use to help you organize your program.