Can changes in nipple appearance occur without being pregnant? 19 years old never had sex with only situation where pregnancy is rare & unlikely

Yes: Nipples on a person will look a little different each year as the person ages. Think of a person's nipples at age 5, 10, 15, 20, 40, 60, and 80 years... And presume the person never got pregnant. One can imagine that the person's nipples would be different at all those age points. Size, color, wrinkling, spots, glands, hairs, etc., on or around the nipples will change.