If you want to do well as a software engineer, focus on your mathematics and computer-based electives in high school. In college, people who pursue computer science degrees are usually expected to finish Calculus III or Calculus IV. The rest of the fundamentals are taught through our curriculum (including how to code). While I was in college, I was taught a few programming languages, the basic principles of how to write good code, and went through applied sciences, Linear Algebra and Calculus. While in high school, it's not likely you'll do much programming, although some extracurricular teams might have coding involved in them. For example, when my sister joined a robotics team, she got to work on programming a robot!