https://www.theverge.com/2018/6/5/17430478/googles-project-fi-children-under-13-family-plan

Google’s Project Fi is now letting users add children under the age of 13 to group plans through a Google account managed with Family Link. The additional functionality lets families with young children share a Project Fi plan and monitor their children’s data use.

Now that Project Fi works with Family Link, users can set data alerts on usage for their accounts and their children’s accounts, and remotely lock their children’s phone when they’ve used too much screen time. You’ll also be able to access content filters on Chrome, Google Search, and other services.