Color.linear

Description

A linear value of an sRGB color.

Colors are typically expressed in sRGB color space. This property returns "linearized" color value, i.e. with inverse of sRGB gamma curve applied.

using UnityEngine;

public class Example : MonoBehaviour
{
    void Start()
    {
        Color newColor = new Color(0.3f, 0.4f, 0.6f);
        print(newColor.linear);
    }
}

Additional resources: Linear and Gamma rendering, ColorSpace, Mathf.GammaToLinearSpace, Mathf.LinearToGammaSpace.