Do hairs grow thicker after being cut?

No. After shaving the hair, it grows back to the same thickness as before, since the bulb of the hair, which determines its diameter, is not removed with the shaver.
We get this impression because the hair of the beard is cut close to the skin, just where it is thicker - from bulb to tip, the hair only sharpens. "It's the same as with grass: when we cut it, it gets stuck, but it does not mean it's thicker," says dermatologist Jane Tomimori Yamashita, a professor at Unifesp. This applies to all body hair (including hair) in both sexes. In the case of girls who use hair removal methods that pull hair out with the root, what can happen is the thinner rebirth wire than the original. "When the device pulls out the hair, it takes part of the bulb and with that the diameter decreases," says Jane. Even then, the cells responsible for hair multiplication are still alive, and if it is not plucked again, then its thickness will stabilize.
Another common false impression is that the hair grows faster when it is cut. In fact, the speed of growth is independent of the number of times it has been cut, unless instead of cutting it it loses the bulb. In this case, it takes longer to grow, because it needs to recompose its root, which is 1 to 2 millimeters below the skin.