I've got an iPad mini 4, running iOS 10.3.3.
When you head to the Settings > Display & Brightness, you can set if you want the iPad to lock when you close the cover/press the power button, as well as set a time for when it automatically locks. This does not, however, require a password.
Is there any way to lock these settings so that a certain person can't keep changing them? There doesn't seem to be a way to do this is the Restrictions or anything, and I can't find anything on how to do this.