Music schools test students on their music theory knowledge often after they’re accepted but before freshman year begins. This is for placement purposes. Some students can pass out of beginning music theory, but most do start there. Music theory is one of the harder classes for music students, so having some background before starting your first college-level music theory class is very helpful. Students can get this through private teachers, summer music programs, AP Music Theory, or online. As for sight singing, many schools will test you on this in your audition. How much bearing it has on your acceptance is up to each school. But it’s a skill that’s really important to learn for college as well as your future career.