Lip serums can give the appearance of fuller lips temporarily, but they do not physically increase the size of your lips permanently.

Many lip serums contain ingredients like hyaluronic acid, which is a humectant that can draw moisture into the skin and give the lips a plumper appearance. Some lip serums also contain ingredients like peptides, which can stimulate collagen production and give the lips a slightly fuller look over time.

However, it's important to note that these effects are temporary and will diminish once you stop using the product. The only way to permanently increase the size of your lips is through cosmetic procedures like lip fillers.

Also, while lip serums can be beneficial for hydrating and nourishing the lips, they should not be used as a substitute for a good lip balm or lip moisturizer, especially during harsh weather conditions. Always make sure to keep your lips well moisturized and protected from the elements to maintain their health and appearance.