No, there aren’t too many kids, there are too many of us older people. The fertility rate has already dropped, the unpopular opinion that would be effective would be don’t let people live past 65 or something like that. If you cut fertility so low, it just makes the population skew even older than it already is. Better to get the average below replacement (it is headed there soon without your mandate) and then hopefully to replacement level at a better population size.