Two kids who were/are on this path. Attended public high school, one reason was higher level maths offered within the school vs some privates.
Here is what we did: Calc AB freshman year, Calc BC sophomore year, Multi/Linear junior year, and then AP Stats. The high school offers Multi and Linear as DE with George Mason.
They will have completed the highest maths available at the high school. The school profile sent to the colleges with the transcripts list the math offerings and show the child completed the most rigorous math classes offered. PS - one of my children were accepted CS at Cornell with highest math being multi/linear. He was also WL at Princeton.
Also here is what MIT says (
https://mitadmissions.org/apply/prepare/highschool/)
Students who are well matched with MIT take the following classes in high school:
Math, through calculus
We know that not all high schools offer the chance to take all these recommended classes, and we take this into consideration when reviewing your application.