How to make a 2D mobile tap jump with small jump and if I Hold a touch it would jump higher

Hi, I have a 2D game that has already a jump michanism. a tap or even a hold would just make it jump with the same force. the jumpforce is 8 which I want it to be the highest jump possible which is a hold not a tap, so a tap would just be 2 or 4, how do I do that?