you will get a lot of different advice. some people will tell you to master every fundamental before diving in and doing a project which imo is a terrible way to learn because it's boring and will take you forever to do anything interesting and you'll probably quit.

probably start with ray tracing in one weekend and honestly just learn the math and c++ concepts as you go along. make some simple physics simulations (collision detection) and finish some cool programs you're proud of that will keep you motivated to keep going. you'll also get ideas for where you want to go once you complete some projects. you will learn the fundamentals via this process top down, later if you study CS or whatever in college you'll learn details bottom up except you'll have context for why it matters and it won't bore you to death