In Frostpunk 2, there are a variety of laws to choose from to increase your population. For example, the "Welcoming Immigration Act" attracts immigrants to settle down; the "Legalization of Child Labor" speeds up the rate of population replenishment. However, each law has its pros and cons, and urban resources and development needs need to be comprehensively considered and decisions made carefully.
There are many laws that can increase population growth when implemented and certain ideas can be presented to the city council after studying them. Here is a list of these laws and details on how to obtain them:
Parenthood: Focus on Motherhood (City Council: Society). Available after studying Parenthood: Focused on Motherhood (idea tree: Society).
Relationships: Relationship Rotation (City Council: Society). Available after researching Relationships: Relationship Rotation (idea tree: Society).
Relationship: Forced Marriage (City Council: Society). Available after researching Relationships: Forced Marriage (idea tree: Society).
Fertility: Family Planning (City Council: Society). Available after researching Fertility: Birth Planning (idea tree: Society). This is a radical idea that requires progress on the rational side.
Fertility: forced procreation (City Council: Society). Available after researching Fertility: Forced Birth (idea tree: Society). This is a radical idea that requires progress on tradition.
Outsiders: Accept all outsiders (City Council: City). Available immediately.
Outsiders: Allow efficient outsiders (City Council: City). Available immediately.