my high school doesn't offer AP

there are two main reasons for AP in terms of college admissions

1. To take college-level courses in high school and submit your high scores so you won't have to take those courses in college (similar to how community college coursework can be transferred)

2. Showing that you're capable of doing well in college-level courses that encompass your interests; basically used to show commitment to your interests + your field

they're not necessarily losing weight in admissions, but some universities, especially highly selective ones, have a limit to how many AP scores you can submit to receive credit at their institution. They'll still see how well you did on all of the exams you choose to advertise scores for, but they only take a certain number.

You could always consider looking into dual enrollment programs to receive college credit, but most programs only apply to in-state schools. You could also self-study AP classes or take AP exams for courses you're already familiar with, and register to take them at the nearest testing location.

College admissions will also consider how many APs your school offers + which ones, so self-studying definitely shows initiative and commitment.