Is the khaki skirt formal?

It's a western-style uniform, which is usually worn by junior high school students, because wearing big breasts is not good-looking and cute. In fact, khaki skirt is a kind of jk vest skirt, which is divided into many different types in JK uniforms. If it is not subdivided, it is mainly sailor suit and suit uniform, but if it is subdivided, there are many kinds inside, including vest skirt, pleated skirt, vest, suit, khaki skirt and so on.