I do believe it's a standard feature for the Prestige trim level. The reason you might not be seeing it working is usually because it's a setting that needs to be enabled in the vehicle's infotainment system. It's not always turned on by default from the factory. Try checking in the main Setup menu on your screen. I'm not 100% certain but you should look for an option like Vehicle, then Doors or Locks, and from there you can usually choose how and when the doors automatically lock. You might have options like "Lock when shifting into Drive" or "Lock based on speed". Something like that.
If you go through the menus and still can't find it, there is a small chance that the setting is disabled due to a regional difference in the car's software, but that's unlikely for such a common feature. Your best bet is to check for a Doors or Locks menu. If it's not there, you should ask the dealership to show you where it is, as they can also enable it for you if it's buried in a deeper diagnostic menu. It's almost certainly a setting you just need to turn on.
