Apple Park is not open to anyone without a pre-approved business reason for entering, including families of Apple employees.
Google is more open to visitors at most buildings, when accompanied by a Google employee with access to the relevant building.
But do note that “campus” is not really a word that accurately describes Google or Apple. They both have a sprawl of buildings strewn about the 5-10 mile radius around the building the CEO happens to have their office in. Some just look like random office buildings, others have a courtyard or other feature that make them feel more like a campus.
But for the most part they aren’t much to look at.