Is there a way to get landmark features automatically learned by a neural network without having to manually pre-label them in the images that are being fed into the network?
No, you can't. In CNN, if you want to detect landmark, you need to prepare data with region box, it's coordinates, width, height, than number of points that should be detected and points coordinates. Then your target vector should be,
This is your target vector. Optionally you can use YOLO algorithm.