If direct admission to a major is more competitive than general undeclared admission, then changing into the major later will be difficult in terms of college GPA requirements and/or competitive admission.
Changing from general undeclared to CS at UIUC, Washington, Texas, UCB, UCLA, CMU will be difficult. But doing so at CSU Dominguez Hills will not be.
For your specific schools, search “[college name] change major [major]” to see how difficult it is.