What technique is used to enhance the appearance of thin lips?

Applying highlighter on the cupid's bow is an effective technique to enhance the appearance of thin lips. Highlighter draws light to the area, creating a visual illusion of fullness and accentuating the cupid's bow, which can make the lips appear more defined and plump. By highlighting this area, it also adds dimension to the lips, making them stand out more prominently.

In contrast, using a darker lip color might actually create a more flattened effect on thin lips, as darker shades can recede and make the lips look smaller. Filling in with concealer may not contribute positively to the desired fullness and could instead wash out the natural color, further drawing attention away from the lips. While matte lipsticks can be used for various effects, they often do not impart the sheen that helps create the illusion of volume, which highlighters can provide. Thus, highlighting the cupid's bow is a strategic choice for achieving fuller-looking lips.