Population decreases are already happening in modernized, wealthy countries, no need to do anything there. The poorer ones will end up starving as the climate collapses, so that’s basically taken care of too. Population collapse isn’t always good, though, somebody has to buy the goods and services.
They’re forced to work 12+ hours a day, every day, if they want to get anywhere. I wonder where the time to find a partner and have children is supposed to come from?