GUILayout.button size is not changin

I used GUIStyle for button. I used fontsize for change the size of the button. It’s not working, also i tried to change the button background texture2D image. It’s also not working. Why?

void OnGUI() { = style;
        GUILayout.Label("1. Print the alphabet image targets located at", style); = style1;
        GUILayout.Label("2. Point any of the animal images", style1); = style2;
        GUILayout.Label("3. Finally your kids able to see the 3D animal render on the screen with sound", style2);
	 = startbtnstyle; 30;
		if(GUILayout.Button("Start", startbtnstyle)){

You need to set button size as it optional parameters in button constructor

if (GUILayout.Button("Start", startbtnstyle, new GUILayoutOption[] { GUILayout.Width(<your_width_int>), GUILayout.Height(<your_height_int>) }))

Try like this,

if(GUILayout.Button("Start",  GUILayout.Width(100), GUILayout.Height(100))){