Ronaldo has an oval facial structure. An oval face is when the length from your forehead to chin is more than the length from your cheekbone to another. It is usually more but in oval facial structure the length from forehead to chin is almost 1 and a half times more.
This facial structure is very versatile because it is neither edgy nor sharp not very round. It is a basic facial structure that can ensure you do not look too out of place even if you try some funky styles. But then there is always the element that some styles suit him much more than the others. Because he has an oval facial structure, his face is basically a slim and narrow one. In this case one can go for styles that focus in the crown area and give definition to his narrow face as well as cheekbones.
Apart from this, the hair type also matters. Ronaldo has thin hair and not a very thick growth as well. That is why he opts for shorter styles only. Also it is much more professional for him as a footballer.
The facial structure is a strong element that has a positive impact on his looks but there are surely several other factors that play role in ensuring that his final look is that of a true icon!