There are many books suitable for high school students to read. In fact, I think that except for some books that are too theoretical, such as:

Newton's "Mathematical Principles of Natural Philosophy",

Einstein's "Theory of Relativity" (← Actually, I recommend reading this, it's really interesting. If you don't understand Einstein's original work, you can read "Illustrated Theory of Relativity": popular science, simple content Easy to understand),

Marx's "Das Kapital" (I am really incompetent in this regard, sigh), etc.

You can read all books except it.