If they could make contact with their souls, their behavior would change immediately. Narcissists would then not care so much about the superficial impressions they make on strangers. Feeling their own authentic selves, they would fundamentally care about not hurting others—because they would feel a union with others on a soul level.
Part of our Soul’s expression is a genuine caring for others. It is empathy for their suffering and the desire not to add to it. Narcissists are missing the awareness of that soul quality that makes people care deeply about each other. They are more interested in using or manipulating people to accomplish their short-term goals. All the while feeling empty inside and needing to fill the void.
Part of your question with regard to Narcissists and their souls is “do they understand what it is?” No. They do not. They can give glib definitions that make them look like they know what they are talking about. But they have never experienced it and therefore do not understand it.