It’s more just sharing things like birth control technology and education.
This whole discussion is actually a sort of win-win scenario, because what proves to lower birth rates more effectively than anything is improved regional health, education, and wealth, so helping along those factors is the biggest impact.
China has forcibly implemented strict birth control policy for decades. They're also forcibly sterilizing ethnic minority populations, Uyghurs in particular:
Ok yes, some people are forcing people. Clearly the person you responded to meant that they, and most people concerned about overpopulation, don't want to force anyone.