If girls are not professional players, their legs will hardly get thicker, but will only get smaller, and then the meat will be more solid (remember it is a little solid, not a muscle), because women's hormones are different from men's, and girls will not have such horrible muscles as boys. If practical, I suggest wing chun boxing, but wing chun boxing is generally rare. If you can find genuine products, it is still very good. Personally, I recommend extreme karate, because it is very practical and beautiful, and it is easier to get started than boxing but not as fast as boxing (boxing can be said to be the most practical martial art, but it is not recommended for girls to practice). If it's ITF, if it's WTF, forget it, because WYF is competitive taekwondo, and its practicality is not very high. Although ITF is better than WTF, I recommend karate because I practice karate. Karate and Sanda are similar, but Sanda is not suitable for girls to learn. What you want to learn depends on yourself. What others say is just a reference.