How would one even break up Google ? You can only shut it down (which would allow competitors to emerge again).
Additionally, separate to instagram / facebook / whatsapp ; possibly also facebook social / facebook marketplace / facebook events ; They should have a level of access that others have. Imagine Yahoo users could subscribe to Facebook events without ever setting foot in facebook.com ... I know it sounds like science fiction, but it's possible. like email....
Or you could break up search / browser / advertising / mobile; search and browser would need to invent other ways to monetize themselves.