[[It’s a comb-over.]]
That looks like a hairpiece
There's no way a guy would wear a hairpiece in which the hairline apparently starts at his eyebrows. Most comb-over guys simply part their hair low and comb it straight over. What Trump does is comb it forward, and then he flips it back. It appears that he has grown it quite long so that he has enough hair to simulate a hairline at his eyebrows, and then have enough to flip it back to cover the rest of his head. Because the hair starts at the side of his head, it is already low to start with, hence the low appearance of the "hairline" in front. It takes a lot of spray to hold the coif in place. That's why he wears baseball caps when he is in windy places.
A guy like Trump can afford hairpieces that no one could detect. There's no way that's a hairpiece (IMHO).