(in the era of ATLA,) Iroh was protective and caring, as well as strong. He invested in the growth of others, and used his power to move the world and people around him in a better direction. He pursued his interests without caring overly much for how others would perceive them. He was absolutely a good example of masculinity IMO.
lipstick rule (i.pinimg.com)
Masculinity rule (programming.dev)