How to change material color to a specific object group's childs..?

This is the script I am currently Using.

I am trying to change all the child of the object group’s color on a specific material.

This is what I have.

public Transform target;
	
public Texture2D colorPicker;
private Texture2D styleTexture;

public int textureWidth = 100;
public int textureHeight = 100;
public bool useDefinedSize = false;
	
public int positionLeft = 0;
public int positionTop = 0;
public bool useDefinedPosition = false;

public Color setColor;

public bool showPicker = false;

void Awake() {
	//If size is not using defined size, resize to Texture Size.
	if (!useDefinedSize) {
		textureWidth = colorPicker.width;
		textureHeight = colorPicker.height;
	}
	//If position is not using defined position, relocate to center of screen.
	if (!useDefinedPosition) {
		positionLeft = (Screen.width / 2) - (textureWidth / 2);
		positionTop = (Screen.height / 2) - (textureHeight / 2);
	}
	//Set up color preview box.
	styleTexture = new Texture2D(1, 1);
	styleTexture.SetPixel(0, 0, setColor);
}

void OnGUI(){
	//If picker is disabled, early return.
	if (!showPicker)return;
		//Color canvas.
		if (GUI.RepeatButton(new Rect(positionLeft, positionTop, textureWidth, textureHeight), colorPicker)) {
			//Get Mouse Position.
			Vector2 pickpos = Event.current.mousePosition;
			int canvasX = Convert.ToInt32(pickpos.x);
			int canvasY = Convert.ToInt32(pickpos.y);
			//Reposition Mouse input according to size and position of the canvas.
			Color col = colorPicker.GetPixel(((canvasX-positionLeft)*((colorPicker.width/textureWidth))),(colorPicker.height-((canvasY-positionTop)*(colorPicker.height/textureHeight))));
			//Return picked color.
			Debug.Log(col);
			//Set Color for display.
			setColor = col;
			}
		//Apply button.
		if (GUI.Button(new Rect(positionLeft + textureWidth - 60, positionTop + textureHeight + 10, 60, 25), "Apply")) {
			//Change material color of all child in the target object.
			foreach(Renderer r in target.parent.GetComponentsInChildren()) {
				foreach(Material M in r.materials) {
				M.color = setColor;
					}
			}
			//target.renderer.material.color = setColor;
			// hide picker
			showPicker = false;
		}
			//Create Style for color preview.
			GUIStyle style = new GUIStyle();
			//Update Color for color preview.
			styleTexture.SetPixel(0, 0, setColor);
			styleTexture.Apply();
			style.normal.background = styleTexture;
			GUI.Box(new Rect(positionLeft + textureWidth + 10, positionTop + textureHeight + 10, 30, 30), new GUIContent(""), style);
		}
}

I get this error :

Assets/Scripts/ColorPicker.cs(59,61): error CS0411: The type arguments for method `UnityEngine.Component.GetComponentsInChildren<T>()' cannot be inferred from the usage. Try specifying the type arguments explicitly

How do I fix this…?
Can anyone point out my mistakes?

You need to specify that you want a renderer component back:

target.parent.GetComponentsInChildren<Renderer>()