So the AOs at relevant colleges I have seen address this have disclaimed they try to fill majors in that sense. Which again wouldn’t make much sense.
Like, suppose your college has an exploratory model where you are expected to take a variety of classes and only decide on your major by the end of your sophomore year. Many people take classes in areas that are not typically offered in high schools, and end up majoring in things they didn’t even think about when applying. In general, a majority end up majoring in something different than they thought they would when applying.
If you are admitting applicants to such a college, how would you “fill” majors? Not only is there nothing stopping a student who says they might be interested in majoring in X from majoring in Y instead, but the whole setup of your college experience is designed to encourage that.
Now, what these sorts of colleges actually do say they do in admissions is look for kids who are truly suitable for that sort of broad exploratory model. So, like, CS kids are constantly complaining about how hard it is to get admitted as a CS major, and of course when CS admits by major it can indeed be one of the hardest these days. But these kids seem to think it can be true even when the college does not admit by major. Usually there is no verification of that, but I could see a certain TYPE of CS applicant not doing well, the type who is all CS, all the time, and is not really all that interested in such a broad exploratory education. If a college like that thinks that a given CS applicant is like that, they may not be interested because they may think that applicant is not really going to thrive in a college like theirs.
But they do admit CS intenders, indeed have been “allowing” their CS major counts to go up and up (not that they really can control it). So who is actually getting admitted? I would suggest if you are a CS intender who also has a strong interest in the arts, that is a good start on convincing them you are actually the sort of person who will thrive in that broad exploratory model.
OK, but then won’t you be better off still saying you are an art intender, and then doing CS instead? They tend to say no, and I don’t really see any reason to doubt them. It just isn’t part of their admissions policies to try to do things like that, because it isn’t their college model either. But they may know if you are a kid who says you are thinking of CS but also really like art, there is a good chance you will be one of those kids who actually finds a different passion in college, possibly art, but possibly neither of those too as you encounter so many new things in college.