To use Screen Time Remote Control correctly, you need to install Screen Time Parental Control on the device you want to monitor. After doing so, and installing Screen Time Remote Control on your own device, you can sync your user account and start monitoring.
The best thing about Screen Time Remote Control is that it not only lets you know exactly what another user does with an Android but also lets you do something about it. You can block any app for a specific time period or set a limit on the daily use of a certain app.
One of the most interesting ways to use Screen Time Remote Control is to check that your kids don't spend too much time on their phones. For instance, you can block videogames in the afternoon or limit the use of social networks after 11pm.
Screen Time Remote Control is an excellent monitoring app. That said, it's a paid tool. You have a 14-day trial period, after which you'll have to pay for the app.