Back when I was in high school, I took achievement tests (what are now SAT subject tests). I did not find them hard after just the regular high school (non-AP) courses in the subjects (and no prep besides the high school courses), and got over 700 in all of them (800 in math level 2, which about 12% of that test’s takers got back then). The (public) high school was not elite; only about a third of graduates at the time went on to four year colleges.
Students on the non-accelerated math sequence who take the SAT subject tests can take math level 1.