The approach used by most famous religious books (bhagavadgita, etc.) is statements with many layers of meanings. For example, such a book might say "do to others what you want others do to yourself" and a well-meaning simpleton gets only the surface level meaning, while a more advanced reader sees the more profound meaning, which might've offended simpletons. So everyone gets exactly as much as useful for them. Metaphors are used for the same reason.
That's a really interesting point, but there's no practical way to do this i.e. to embed multiple layers of meaning into Public Communications.
The rules for Public Communications are the same as they are for branding: Consistency, Clarity, Authenticity. A simple, legitimate message, repeated consistently. "Keep Calm and Move On". "Get Vaccinated". "Wear a Mask". etc..
