Sun in the first house makes a person noticeable even when they are not trying to demonstrate anything. There is a natural sense of presence in them: they enter a space, and people begin to take them into account. Sometimes this is expressed brightly, confidently, almost royally; sometimes more quietly, but still visibly. The first house is connected with the body, image, first impression, gait, manner of speaking, and the right to occupy a place in the world, so the Sun here is hard to hide.
Such a person often feels from childhood that people are looking at them. They are given the floor, expected to react, evaluated, compared, singled out. This can become a strong support: they get used to being an active participant in life, not background scenery. But the same thing can create inner tension, as if they must constantly look confident, worthy, and stronger than they actually feel inside.

