Some people have extra layer of fat on their neck, giving them the appearance of a double chin, if you are looking to reduce it, there are a few exercises that can be effective.

1. By performing some neck rotations. Such as Sit or stand up straight and slowly turn your head to the right and then to the left, as far as you can comfortably go. Repeat this method like 10 times.
2. By trying some chin lifts. You can Start by looking straight ahead, then slowly lift your chin up as high as you can and hold for a few seconds. Repeat this method like 10 times.
3. By trying some neck rolls. Start this by looking straight ahead and then slowly roll your head forward, back, and to each side.
4. By trying some standing ear-to-shoulder stretches. You can Start this by standing up straight and then bending your head so that your right ear is near your right shoulder. So try to Hold this position for 15 seconds and then repeat on the other side.
5. You can as well try a seated ear-to-shoulder stretch. You can start this by sitting up straight and then bending your head so that your left ear is near your left shoulder. You should try Hold this position for 15 seconds and then switch sides.
6. By trying some lateral neck flexion exercises.