Transfer game profile from parent account to child accont

You cant. Nothing is transferrable between accounts.

That being said as long as the Xbox he uses has been set as the home xbox for your account then any account that is on the same system will be able to play the games purchased by your account. Game saves/online progression however wont transfer and cant
be transferred.

To share games you should set the account that purchased the games as xbox home and the parental account should allow the child account through privacy settings

You can't transfer profile stats from one account to another

you can indeed transfer money from a parental account to a child account, can be done accidentally too, not sure if there is a way to transfer back as child account cannot transfer money.

You can't transfer licenses or content from one account to another.

The accounts Parent / Child are separate accounts. The parent account just manages the child account.

The child account will remain a child account until the birth date that was used for that account reaches the age of 18.

Why dont they just add this to parental controls? Parents can go and set it up to automatically block certain words on their childs acconts and also notify them when their child uses the blocked words in their messages.