world building does come, it's just done one a first hand experience way until he comes across knowledge he can access. Like right now, his family is going to kick him out because his original body had no magic and thus he was a useless child. And the village he is living in is like bumblefuck territory.
If he shows his family that he can use magic just so he can access their library or get teachers, his family may force him to stay in town to take over the eldest spot of a small village in the middle of nowhere. While his brother will be allowed to leave, staying within the family to get a high paying job in the capital because he has magic, like the other siblings in his family. That stepmother is true worthless bitch.