Presumably, each school’s web site would have its policy on deferral of enrollment, including whether it is allowed and what conditions must be met.
Generally, taking college courses after leaving high school puts the student as risk of no longer being allowed to apply as frosh, although non-credit courses could be a gray area. Each school may have its own policy on what college course enrollment after leaving high school disqualifies the student from applying as frosh, so check each school carefully.
But also check whether merit scholarships of interest are available for gap year applicants, since there may be a few merit scholarships available only to students enrolling in college immediately after high school graduation.
Science undergraduate + law degree could open some possibilities regarding patent or intellectual property law that may not be available to other law graduates.