I currently attend a small high school in rural Indiana. I really want to attend a top-20 school. Does where you go to high school matter? Do you have to attend a top-notch high school in order to have a chance of getting into an Ivy League school? Our high school is ranked pretty low btw.
Where you go to school does not matter near as much as what you do with it.
Our small rural HS ranks about 15 on a 100 point evaluation scale and we send students to Ivies almost every year.
No, there are plenty of elite (not to mention expensive… $35,000 a year) private high schools that have kids rejected from the Ivies, whereas plenty of public schools have sent dedicated students to Ivies,
I hope they do, because if A+ is considered a thing than almost nobody has an A+ average where I go to school and it’s selective. My school doesn’t rank either 
A 4.0 from a competitive HS will stand out more than a 4.0 from an average HS.
Even so, I don’t think colleges take schools into consideration too much. I’m in the 14th worst HS in my state, but last year, a student got into Yale! Your GPA, scores, & class rank are more important.