I myself am a highschool student. I go to school in a Likely D county that swung strongly democrat in 2016 and 2018 and my district encompasses mostly Lean D precincts that swung strongly to democrats both those years.
This school is overwhelmingly Republican, and that title extends from disgruntled Never-Trumpers to Turning Point America and PragerU addicts to the, uh, you know. Of course there are a lot of democrats but I would say that a plurality if not a majority of my peers are right of center.
The overall mood among students is a disliking of Trump's personality but support of his policies. There is no liberal group here but there is a Young Americans for Freedom group (which I am a part of) which has about 70 members, and most of them are actually female surprisingly. I will say my school is mostly white (about 75%) but it still goes to show that from an insider perspective, the "Gen Z is liberal" meme is bogus and is being pushed on us without a basis.
Your basis is literally "my high school is overwhelmingly republican." That's it.