To comport yourself is to behave in a particular way, especially in a careful, public, or formal situation: how you hold your body, how you speak, whether you stay calm. You almost always need that extra word yourself (or himself, herself, themselves). “She comported herself with dignity” means she behaved with dignity. Without the yourself bit, the sentence often sounds unfinished. This is formal, a little old-fashioned; everyday English just says behave or act. Though actually, there is a second, also formal, use: if something comports with a rule or a fact, it fits it — it does not clash. Lawyers like that second use. The first use — how a person carries themselves — is the one learners meet in stories and speeches. The old picture in the word is “to carry”: you carry yourself a certain way.