My engineering kids didn’t use AP to graduate early; they used it to graduate in 4 years! Thanks to AP credit, they were able to take a reduced course load (12-15 hours per semester instead of 16-17). The lighter course load allowed them to keep a high GPA and be more involved in campus activities.
OP - some of our AP teachers were terrific, and some of the courses were really difficult. Your student will benefit from them, in my opinion.