As someone who grew up in a conservative religious bubble, it's a mix of:
Watching their parents and other relatives interact
Parents literally telling their kids "this is how you should treat your wife"/"this is how you should behave for your husband"
Church sermons on the duty of wives to husbands, the husband being the head of the household, etc. - this stuff is explicitly in the Bible so it comes up quite a bit
Teachers in religious schools lecturing about the purpose of marriage and the aforementioned Bible verses
As someone who grew up in a conservative religious bubble, it's a mix of:
Watching their parents and other relatives interact
Parents literally telling their kids "this is how you should treat your wife"/"this is how you should behave for your husband"
Church sermons on the duty of wives to husbands, the husband being the head of the household, etc. - this stuff is explicitly in the Bible so it comes up quite a bit
Teachers in religious schools lecturing about the purpose of marriage and the aforementioned Bible verses