Let's try the costco website, I can see the heated power folding mirrors there on the Level 1 & 2 Big Horn.
https://www.costcoauto.com/new_cars/buildvehicle.aspx?trimid=410849
In looking at how they word the power folding, it's possible the level 1 is a power adjusted but manual fold... but I'm really doing some mental gymnastics lol. I think if you got the level 2 you have power heated mirrors.
"LEVEL 2 EQUIPMENT GROUP
[+]
-inc: Radio: Uconnect 4 w/8.4" Display, Google Android Auto, 1-Year SiriusXM Radio Service, SiriusXM Satellite Radio, Integrated Center Stack Radio, For More Info, Call 800-643-2112, 8.4" Touchscreen Display, Apple CarPlay, Rear Window Defroster, Blind Spot & Cross Path Detection, Power-Folding Mirrors, Power Adjustable Folding Heated Black Tow Mirrors, LED Tail Lamps, Rear View Auto Dim Mirror, Power Adjustable Pedals, Leather Wrapped Steering Wheel, Rear Power Sliding Window, Rear Dome w/On/Off Switch Lamp, Front Fog Lamps, Glove Box Lamp, Footwell Courtesy Lamp, 115V Auxiliary Rear Power Outlet, Dual Remote USB Port, Heated Front Seats, Heated Steering Wheel, Foam Bottle Insert (Door Trim Panel), Wheels: 18" x 8.0" Polished Aluminum, Dampened Tailgate, Security Alarm, Locking Lower Glove Box, Remote Start System, Steering Wheel Mounted Audio Controls, Air Conditioning ATC w/Dual Zone Control, Dual Glove Boxes, 115V Auxiliary Front Power Outlet, 400W Inverter, Cluster 7.0" TFT Color Display, Universal Garage Door Opener, Sun Visors w/Illuminated Vanity Mirrors, ParkSense Front/Rear Park Assist System"