Self-tanner for the face usually comes in the form of a spray-mister or drops.
Your face is delicate, so try to choose a self-tanner formulated for the face and to your specific skin type.
However, if your skin isn’t acne-prone or sensitive, you can get away with applying a body tan to the face, but make sure it’s been diluted with a water-based moisturiser (oil will react with the tan).