Yes, it is possible to overstretch your foreskin. Overstretching can cause discomfort, pain, and even injury. It is important to follow the instructions provided with a foreskin stretching device, such as a foreskin expander kit, and to be gentle during the stretching process.
It is also important to listen to your body and stop if you experience any discomfort or pain. If you are unsure about how to stretch your foreskin safely, it is recommended to consult with a medical professional for guidance.