Windows 10 - Auto-lock the computer on a schedule (e.g. at bedtime)

Create the following xml file:

<!-- SPDX-License-Identifier: CC0-1.0 -->
<Task version="1.2">
<RegistrationInfo>
<Description>Lock session at night.</Description>
<URI>\lock-session-bedtime</URI>
</RegistrationInfo>
<Triggers>
<CalendarTrigger>
<StartBoundary>2020-01-01T23:45:00</StartBoundary>
<Enabled>true</Enabled>
<ScheduleByDay>
<DaysInterval>1</DaysInterval>
</ScheduleByDay>
</CalendarTrigger>
</Triggers>
<Principals>
<Principal id="User">
<LogonType>InteractiveToken</LogonType>
<RunLevel>LeastPrivilege</RunLevel>
</Principal>
</Principals>
<Settings>
<MultipleInstancesPolicy>Parallel</MultipleInstancesPolicy>
<DisallowStartIfOnBatteries>false</DisallowStartIfOnBatteries>
<StopIfGoingOnBatteries>false</StopIfGoingOnBatteries>
<AllowHardTerminate>true</AllowHardTerminate>
<StartWhenAvailable>false</StartWhenAvailable>
<RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable>
<IdleSettings>
<StopOnIdleEnd>false</StopOnIdleEnd>
<RestartOnIdle>false</RestartOnIdle>
</IdleSettings>
<AllowStartOnDemand>true</AllowStartOnDemand>
<Enabled>true</Enabled>
<Hidden>false</Hidden>
<RunOnlyIfIdle>false</RunOnlyIfIdle>
<WakeToRun>false</WakeToRun>
<ExecutionTimeLimit>PT0S</ExecutionTimeLimit>
<Priority>7</Priority>
</Settings>
<Actions Context="User">
<Exec>
<Command>%WINDIR%\System32\rundll32.exe</Command>
<Arguments>user32.dll, LockWorkStation</Arguments>
</Exec>
</Actions>
</Task>

NOTE: Modify the hour and minutes in the StartBoundary to set your own log-out time (the date just needs to be any date in the past).

Take care not to make any other changes to the file.

Open the Task Scheduler program (use the search field in the Start Menu to find it.)
Expand the Action menu in the menu bar and select Import task.
Choose the xml file created above, and click OK.

NOTE The task will be called lock-session-bedtime.

The scheduled time can be changed, or the task can be removed from inside the Task Scheduler as needed.