To see what your child is doing at that moment on their devices,

If your child is using their device at that time, you will be able to see a screenshot of your child's device along with details of the app/website they are using. You can change the rules of the app/website by tapping on the rule button from here.

This will not work if the child's devices are not connected to the internet.

You can also view all of their activities on the Activity page.