Yes, folding knives can be used to cut leather. However, the ease and effectiveness of cutting leather with a folding knife may depend on several factors such as the sharpness of the blade, the size and shape of the knife, and the thickness and type of leather being cut. Its important to use a sharp and well-maintained blade, as a dull blade may not cut through leather cleanly and could potentially damage it. Additionally, using a knife with a thinner and more pointed blade, such as a utility or craft knife, can provide better control and precision when cutting leather.