Version: 2017.2

QualitySettings.resolutionScalingFixedDPIFactor

マニュアルに切り替える
public static float resolutionScalingFixedDPIFactor ;

説明

In resolution scaling mode, this factor is used to multiply with the target Fixed DPI specified to get the actual Fixed DPI to use for this quality setting.

using UnityEngine;
public class StartupExampleScript : MonoBehaviour
{
    void Start()
    {
        // Set the target Fixed DPI for this quality setting to be half of the default.
        QualitySettings.resolutionScalingFixedDPIFactor = 0.5f;
    }
}

関連項目: Quality Settings.