public class ScreenShotRect : MonoBehaviour {

    public RectTransform rectT; // Assign the UI factor which you wanna seize

    personal int width; // width of the article to seize
    personal int top; // top of the article to seize
    personal Transform rectTransformParent;  //RectTransform father or mother to reasign after utilization
    personal GameObject screenShotGO;    //Tempory GameObject to repeat recttransform
                                        //RectTransform values to reasign after utilization
    personal Vector2 offsetMinValues;
    personal Vector2 offsetMaxValues;
    personal Vector3 localScaleValues;

    // Update is named as soon as per body
    void Update()
    {
        if (Input.GetKeyDown(KeyCode.Space))
        {
            if (rectT != null)
            {
                if (rectT.root.GetComponent<CanvasScaler>().uiScaleMode == CanvasScaler.ScaleMode.ScaleWithScreenMeasurement)
                {
                    if (rectT.root.GetComponent<CanvasScaler>().screenMatchMode != CanvasScaler.ScreenMatchMode.MatchWidthOrHeight || 
                        rectT.root.GetComponent<CanvasScaler>().matchWidthOrHeight != 0.5f)
                    { 
                            Debug.LogWarning("UI might not look the identical attributable to Canvas Scaler both screenMatchMode was not set MatchWidthOrHeight or MatchWidthOrHeight isn't set to 0.5f");
                    }
                    createCanvasWithRectTransform();
                }
                else if (rectT.root.GetComponent<CanvasScaler>().uiScaleMode == CanvasScaler.ScaleMode.ConstantPixelSize)
                {
                    StartCoroutine(takeScreenShot());
                }
                else
                {
                    Debug.LogWarning("Canvas Scaler mode not supported.");
                }
            }
            else
            {
                Debug.Log("Rect rework is null to seize the screenshot, therefore fullscreen has been taken.");
                Application.CaptureScreenshot("FullPageScreenShot.png");
            }
        }

    }

    personal void createCanvasWithRectTransform()
    {
        rectTransformParent = rectT.father or mother; //Assigning Parent rework to reasign after utilization

        //Copying RectTransform values to reasign after switching father or mother
        offsetMinValues = rectT.offsetMin;
        offsetMaxValues = rectT.offsetMax;
        localScaleValues = rectT.localScale;

        //Creating secondary CANVAS with required fields
        screenShotGO = new GameObject("ScreenShotGO");
        screenShotGO.rework.father or mother = null;
        Canvas canvas = screenShotGO.AddComponent<Canvas>();
        canvas.renderMode = RenderMode.ScreenSpaceOverlay;
        CanvasScaler canvasScalar = screenShotGO.AddComponent<CanvasScaler>();
        canvasScalar.uiScaleMode = CanvasScaler.ScaleMode.ConstantPixelSize;
        screenShotGO.AddComponent<GraphicRaycaster>();

        rectT.SetParent(screenShotGO.rework);    //Assigning seize recttransform to non permanent father or mother gameobject

        //Reasigning recttransform values
        rectT.offsetMin = offsetMinValues;
        rectT.offsetMax = offsetMaxValues;
        rectT.localScale = localScaleValues;

        Canvas.PressureUpdateCanvases();   // Forcing all canvas to replace the UI

        StartCoroutine(takeScreenShot());   //Once the whole lot was set prepared, Capture the screenshot
    }

    personal IEnumerator takeScreenShot()
    {
        yield return new WaitForEndOfFrame(); // it should be a coroutine 

        //Calcualtion for the width and top of the screenshot from recttransform
        width = System.Convert.ToInt32(rectT.rect.width);
        top = System.Convert.ToInt32(rectT.rect.top);

        //Calcualtion for the beginning place of the recttransform to be captured
        Vector2 temp = rectT.rework.place;
        var startX = temp.x - width / 2;
        var startY = temp.y - top / 2;

        // Read the pixels from the feel
        var tex = new Texture2D(width, top, TextureFormat.RGB24, false);
        tex.ReadPixels(new Rect(startX, startY, width, top), 0, 0);
        tex.Apply();

        // break up the method up--ReadPixels() and the GetPixels() name inside the encoder are each fairly heavy
        yield return 0;

        var bytes = tex.EncodeToPNG();
        Destroy(tex);

        //Writing bytes to a file
        File.WriteAllBytes(Application.dataPath + "/ScreenShotRect/ScreenShot.png", bytes);

        //In case of ScaleMode was not ScaleWithScreenMeasurement, father or mother won't be assigned then no must revert the adjustments
        if (rectTransformParent != null)
        {
            //Reasigning gameobject to its unique father or mother group
            rectT.SetParent(rectTransformParent);

            //Reasigning recttransform values
            rectT.offsetMin = offsetMinValues;
            rectT.offsetMax = offsetMaxValues;
            rectT.localScale = localScaleValues;

            //Destorying non permanent created gameobject after utilization
            Destroy(screenShotGO);
        }

        Debug.Log("Picture taken");
    }
}

Note: UI might not look the identical when Canvas Scaler both screenMatchMode was not set MatchWidthOrHeight or MatchWidthOrHeight isn’t set to 0.5f

This code is modified based mostly on Shuvro Sarkar‘s reply