dragging spinning wheel

I am a beginner in unity So, I wanted to Make A Fortune Wheel But Instead of Rotating it with a button I want Like, the speed of its spinning will depend on how fast I touch n’ dragged the wheel itself. If I flick/rotate it very fast, the wheel would go spinning faster.But if I only moved it slowly, then it would barely spin at all.,

So, you want to set a variable like speed, to the magnitude of the swipe,
then, after swiping you want to slowly decrease that value.

something like this:

speed = (touch.pos.start - touch.pos.end).magnitude
*touch exit happens*
wheel.rotate(0,0,speed);
if(speed > 0)
speed -= Time.deltaTime * slowdownAmount;