True, the better your stats, the more likely you are to be admitted (except at schools that practice yield protection against “overqualified” applicants). Yes, at many schools, your intended major does make a difference in admission selectivity (and some schools have secondary admission to some majors after enrolling).
However, a true safety is one where admission is assured for you, affordability is assured for you, and your intended or possible majors are available and accessible to you. Early action or early rolling admission schools can become early safeties if they admit you early.