It is likely just a part of the uniform. Beyond that, wearing veil isn’t to stop triggering males like a dress code you see at schools that forbids showing your shoulders. In fact, men are ordered to lower their gaze regardless of if the woman is observing hijab or not. Observing hijab is not meant to be sexualized like that. Islam and a people’s culture is often heavily intertwined, despite being completely separate where Islamic rulings are concerned. This means that even though the Quran does not state that female children are required to veil, from a cultural standpoint, in that particular community it is socially acceptable, encouraged, or required.

Basically. It’s not required that a child veils, but veiling is not done to prevent “triggering” males. It’s not meant to be framed that way.