None of the dual camera dashcams have this feature.
It have allso been debated weather it will be usefull, the dual cameras are for mounting inside the car, so in case of a sedan the trunk will block the view.
But i SUV or 4x4 with a flat rear end can be covered by the rear camera if it is tilted more than usioal Down towards the ground, rear dashcams are not meant for covering the cruisioal first feet behind a car like a dedicated reverse cam do as it cover from the bumper ( where they are often mounted Down low ) and 16-20 feet behind the car in clear view.
None of the dashcams have a sensor to feel when reverse is engaged, but some have PIP and touch so it is just 1 push and the reverse camera will be on screen.
But then another issue pop up, most dashcams sit up high in front of mirror so the screen wil be blocked from view, that in turn might be resolved by using a AV out on the dashcam, but then in you will have to have a double din headunit with a screen that can display the footage, or buy a small LCD screen to Mount on the dashbord.
you are best off buying a dedicated reverse camera setup ( witch will have guidelines and distance lines in the footage ) and then a dashcam with 1 or 2 cameras to record the traffic around your car.