Unity - How to take a screenshot in game with script (at a specific resolution)

Attach below script to any object in your game. Click Play in editor and at the desired point, press "z" in keyboard to take your screenshot as a png file (if game is built, use Ctrl-Z). The screenshot will be stored (ie; the save location) in your Unity project's root folder

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class TakeScreenShot : MonoBehaviour {

 // Update is called once per frame
 void Update () {
#if UNITY_EDITOR
        if (Input.GetKey(KeyCode.Z))
#else
     if((Input.GetKey(KeyCode.RightControl) 
      || Input.GetKey(KeyCode.LeftControl)) 
        && Input.GetKeyDown(KeyCode.Z))
#endif
        {
            Debug.Log("Taking screenshot");
            ScreenCapture.CaptureScreenshot("ScreenShot-" + 
             UnityEngine.SceneManagement.SceneManager.GetActiveScene().name + 
             ".png");
            Debug.Log("Done");
        }           
    }
}

Tip: If you want a specific resolution of screenshot, make sure to set this in the player (ie; in Game tab)
In the below example, we are setting resolution to 2400 x 1200. When you use above script, the saved screenshot will have the same resolution.

See example below. Use + symbol to add custom resolutions