core workouts for a smaller waist

Hey there, I'm reading lots of conflicting info about ab exercises that give you a snatched vs straight core profile. The 'experts' on the web are all over this place if this is a thing or not.

What do FB folks think? What's the science? If i have had more of an hour glass in the past, are there exercises that support getting back to that vs others that build more of a straight (albeit fit) waist?

thanks, be well! brooke