No Way!!! That is flat out false! ORD & LAS: you are incorrect, mistaken, mispoken, and guilty of spreading misinformation! Now take a deep breath and pay attention: "No one under the age of 21 will be allowed to check into any Harrah's Las Vegas property, if unaccompanied by a person over 21.". Period. End of story. You are wrong like hitting on 17! And if you are inferring that Harrah's employees are exempt from this policy and may check into a room if they are under 21: again, that is entirely untrue and against Harrah's policy as well! You don't know what you're talking about!
I refer you to the Harrah's Room Reservation Age Requirement, as published in the Harrah's T's & C's, below:

Harrah's Room Reservations Terms And Conditions: https://www.harrahs.com/reservations...p?propCode=LAS

Or call Harrah's reservation dept. and ask them yourself: 1-800-214-9110 or 1-800-HARRAHS