If you are not looking to impress colleges, then just study the material on your own without sitting for an exam. Just for the intellectual curiosity.
Does your high school order the test for you and allow you to take it in school with students who actually took the class? Many schools will not allow it - they will only allow you to sit for it if it’s a course they don’t offer. And even that can be a struggle. Most schools are trying to tame the AP rat race.