Cloth.bendingStiffness

Description

Bending stiffness of the cloth.

Must be between zero and one. Setting the value to zero disables bending stiffness simulation.
In many cases, when you want a cloth to be more stiff, actually reducing the number of vertices will get you better results - and performance.

using UnityEngine;

public class Example : MonoBehaviour
{
    void Start()
    {
        GetComponent<Cloth>().bendingStiffness = 1;
    }
}