Declaring a major not wise idea?

You need to research each school. Many larger universities will direct admit your DD into the CS department. That requires her to declare at least the general area of study up front. It’s preferable to do that if it is an option. CS majors are very competitive. You don’t want DD to attend college for a year and find out she can’t study CS after all because her GPA isn’t a 3.75+ - or simply because the department is already oversubscribed. This actually happens at some schools, including UIUC. I believe Purdue is another school where some majors can be direct admit, and if you don’t start in the right department, you have to apply to change into the new one, and there are no guarantees you’d get approval. You might have better luck in some LACs, but my point is to research carefully.

For some majors in some colleges, it might work, but it probably isn’t a very safe strategy for STEM majors these days. It’s also not a great idea to start an application based on a lie, but your DD is the one who has to live with the results.