Though boilerplate is never acceptable, most of that is constant-factor overhead, not per-triangle overhead, and tutorialspoint is not a site you should trust under any circumstances. See my links above for better sources.

If you put more vertices and indices in Step 2 you can draw an arbitrarily complex 3-D object with this same code.

And there's a lot of stuff in GLSL where you can program directly with high-level concepts like vectors, normals, and partial derivatives, instead of expressing them by hand the way you would in C.