Google Family Link is a free app that allows you to guide your child's use of Android devices (mobile phone and tablet). With Google Family Link, you can, among other things, define which content your child can access, track the location and set daily usage times. It thus falls under the category of technical child protection, although it is up to you how strict you want to be with the settings and whether you want to use it to monitor your child or merely protect them from unpleasant content.