Most colleges have a music department and major (for a BA). The curriculum may vary a bit (for instance, Brown has three strands in its music major, composition/theory, ethnomusicology and technology; Wesleyan tends toward world music, and so on, so look at the music department, curricula, courses and requirements for each school. Some do have an applied music component, meaning performance, in classes, or by providing for lessons, or by giving credit for performance. You really have to look into details.
In general, a BA music major will study theory./aural skills/musicianship, some composition, music history, ethnomusicology, and technology/electronics. Some courses may cover folk, jazz, rock but many courses will be focused on classical. (I might add that one of my kids majored in music without even touching an instrument.)
Your son can deepen his interests in music both in and out of the classroom. He can take lessons and classes, and perform in extracurricular ensembles. His music may blossom. He can also take physics classes and see what he wants to do once on campus. Has he taken any theory? He may even find he does not like academic study of music and wants to keep his music separate from his studies who knows. Or he may love music classes.
Music education is a different major than general music. Often state universities offer music education. There are auditions but in general the fact that your son plays several instruments would seem to be an asset for that field, if he continues to develop. He can look into programs for undergrad but there are also grad programs.
I don’t know what part of the country he is interested in. He can choose based on location, size, academics and “vibe” like anyone else as long as the departments he is interested in check out after research. Let us know what part of the country he wants to be in and maybe we can suggest some schools.
I recommend a book I found online entitled “Creative Colleges” that has sections on music, theater, dance, art, and writing. Good uck!