Yes, you can change majors once accepted but impacted majors usually have higher standards for acceptance so they can be more difficult to switch into later. If applying for an impacted major, select a non-impacted major (if possible) as your alternate. Since you are interested in the CSU’s, here is a link indicating which majors at each campus are impacted. Nursing is impacted at all CSU campuses.
https://www.calstate.edu/sas/documents/impactedprogramsmatrix.pdf