A Rectangle Shaped Body

To flatter your rectangle shaped figure, will be to maintain the figure balance that you already have. Then create the illusion of a defined waistline so that you look more like the ideal hourglass that we all want. Avoid those styles, such as shifts or trapeze dresses that hide your shape. The exception would be for women who wear those extra-small sizes.
You can always get away with these styles because of your small size. Although, if you’re size 6 or above, you’re better off going with the strategy of creating an illusion of an hourglass figure. For example, avoid styles that tend to over-emphasize either bust or hips. If you wear a gathered skirt, your hips will look bigger and make you bottom-heavy. Likewise, if you wear an off-the-shoulder top, you may find that you appear top-heavy.
Another other big challenge will be to create the illusion of a defined waistline. By placing emphasis on the waist or midriff, you appear to have a defined waistline thus your figure will take on that more shapely look. Wearing straight, dark-wash jeans will makes you look taller.