When your kid with a Google Account turns 13 (or the applicable age in your country), they can have their parent continue to manage their Google Account or decide to graduate into a self-managed Google Account.
After graduation, your kid will be able to sign into YouTube and have access to all of YouTube’s content and features, such as live streaming, uploading, sharing, and commenting on videos. Your kid won't be able to use YouTube Kids with their Google Account anymore, 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 kids turns 13 (or the applicable age in your country).