Until when parents are supposed to care about their children?

Define "care": The states define parental control/ consent over kids to a specific age, commonly 18. The state expects parents to provide subsistence, shelter and guidance, but not much else.After a kid reaches the point the state considers them a self consenting adult, the parent may choose to provide for them or not. They may "care" emotionally for life, but they are not required to subsidise them forever.

Always: You will always care for your children, but they should be able to be independent in most things by age 18-21 depending on the child.