You might not have seen it obviously mentioned since it's a standard feature and not something you need to select, it's part of their smart access system. Did you search the Lexus website? Took me a minute to find that.
The SmartAccess* keyfob lets you lock and unlock your doors and start the push-button ignition—all without having to take your keys out of your pocket or purse. As soon as the sensors detect the presence of your SmartAccess key, the door unlocks when you touch a front-door handle.
STANDARD ON: RC 350 F SPORT, RC 350