Have severe anxiety and panic attacks involve health anxiety, can that make more saliva and nasal congestion?

That can happen: Runny noses or sniffles are common to people of all types once in a while. "Severe anxiety and panic" tends to exaggerate a person's perception of bodily symptoms, and also tends to create thoughts, actions, and habits that increase bodily symptoms. Those are two reasons why one's psychiatric issues need to be treated, not just the bodily symptoms like nasal congestion.