yes but Training the shoulder girdle with delt and trap Training (a part of the back yes but involved in a lot of shoulder moves) is paramount to a wide look. In the old Days they used padded shoulders in suits. posture is also important, i see the effects of muscle distbalance every day in the gym. straightening up and pulling your shoulders back makes a visible difference.
Performing lateral movements have their impact on wideness, but that's only limited. The back, and the serratus as well (pull overs!) is an important foundation for wideness.
Yeah, posture is another important aspect. To improve this, I see many gym rats performing rear delt exercises, but they don't know how to train their backs correctly.