If you have a big skeleton, even if you are relatively light, you may look "bigger" than someone with the same weight but a smaller skeleton. In addition, if your body fat content is low, your bones and muscles will be more prominent, which will make you look bigger in appearance.
In addition, everyone's figure proportion and figure are unique. Sometimes we may feel that one part of ourselves (such as our legs) is more conspicuous than others, but this does not necessarily mean that this part is bigger than others.
Generally speaking, knowing your body composition and proportion and choosing clothes and exercise methods that suit you can make your appearance more in line with your actual weight and figure. At the same time, maintaining a healthy lifestyle, increasing muscle content and reducing body fat rate can also make you look healthier and "thinner".