“Time” → “Schedules”. “School” (Mon–Fri 08:30–14:30) and “Sleep” (every day 21:00–07:00) are already there — off at first. Turn one on with its switch, or tap the pencil to change the days, times and exceptions — apps that keep working during the schedule. “Add a schedule” makes your own.
“Warn 5 minutes before the start” — the child sees a warning 5 minutes and 1 minute ahead, to finish the game. On by default; on some phones only as a notification.
An alarm during “Sleep”. An alarm set beforehand rings during a schedule or a break too: the “Clock” notification appears at the top with “Snooze” and “Dismiss”, and both work. Opening the Clock app itself — to set, change or turn off an alarm — the child can do only if you added “Clock” to that schedule's exceptions: “Time” → “Schedules” → the pencil next to “Sleep” → “Exceptions”. Otherwise set the alarm before “Sleep” begins.
During a schedule the child still has ordinary calls and SMS, the home screen, SOS and KidPair. The free version has two schedules; more with the subscription.