Here is where you can find the exams from the past couple years (more accurate to what you’ll be doing): https://apcentral.collegeboard.org/courses/ap-united-states-history/exam?course=ap-united-states-history
Here are some other old ones that can be useful: https://apcentral.collegeboard.org/courses/ap-united-states-history/exam/the-exam-prior-to-2014-15?course=ap-united-states-history