So, just like that Mercedes CLS I was talking about. It will keep itself in its lane and slow down for any speed limit that it detects. My point of that entire wall of text was that this detection of limits is unreliable, because in real life the signs are sometimes placed in such a way that the cameras detect them as applying for the road you are currently on while in reality they do not.
Tesla Model 3 has this feature and, while autopilot is engaged, will decrease the speed of the car when the speed limit decreases.