If an adult wants to mutilate themselves then that's their choice. A child is not old enough to make that decision. If a young child tells you that they feel like a girl in a boy's body then they're just regurgitating something that their parents or another adult put into their head. Children react to and mimic suggestions from adults, it's how nature designed us to learn from our parents. The problem arises when you have parents that are lefty zealots who want their children to be pawns of the trans mafia and convince their children that they want it also. Then you have children doing irreparable harm to their bodies which will destroy their lives.
But they are not doing it to themselves.