It's quite easy to achieve: have women to be manly for. One child policy ruined the life of hundreds of millions of men.
Wait, I thought that was already the effect, no? With men outnumbering women by a good margin, surely men would try to "out-man" each other to find a mate?
Nowadays we do things more civilized by posing on social media with gym bods and expensive cars and other displays of sexual fitness. Trying to lure a mate instead of taking one.
Unfortunately, the numbers are what they are: a ~30 million gender imbalance. So however you turn it there's going to be 30 million men without a wife/family no matter what they do. Not a good thing if you want society to remain peaceful.
So they either import more women (via force or promise of a better living standard), or they get rid of the excess men (via war), or they suppress them with heavy policing and entertainment doping until the gender imbalance fades out over the next generation or so.