When a child with a Google Account turns 13 (or the applicable age in your country), their parent can continue to manage their Google Account or they can decide to graduate to a self-managed Google Account.
After graduation, your child will be able to sign in to YouTube and have access to all of YouTube's content and features, such as live streaming, uploading, sharing and commenting on videos. Your child won't be able to use YouTube Kids with their Google Account any more, and videos and channels that were previously blocked may be available to watch in the YouTube app.
Learn more about how Google Accounts work when your child turns 13 (or the applicable age in your country).