When children are sensible, give them an abstract and metaphorical explanation.
According to the child's gender, teach her/him the corresponding knowledge and life experience, and use more masculine videos to guide the child to establish a correct concept. Yes, boys can show him the National Day military parade and so on to cultivate his masculinity.
Let children communicate with men in family members, such as grandfathers and grandfathers. And absorb masculinity from them.