Thank you.
If a child is under the age of child protection in the jurisdiction where they reside, then the child protection authorities would become involved and stand in on behalf of the child, for any act, in terms of requesting a peace bond or any other intervention with the family to help them become aware of the harmful impact of forcing a child into a marriage.
Normally that would be the role for the child protection. However, if the child is over the age and speaks to a victim services worker, that person could apply for the peace bond on behalf of the child. It's the same if the child contacts the police; usually it is the police who apply for peace bonds on their behalf.