Change Shader, Make Object Transparent

In Unity Editor: Edit > Project Settings…
Add Legacy Shaders/Transparent/Diffuse

In the code file: var shader = Shader.Find("Legacy Shaders/Transparent/Diffuse");

foreach (Transform child in MyGameObject.transform)

{

var renderer = child.GetComponent<Renderer>();

foreach (var material in renderer.materials)

{

     material.shader = shader;

     material.SetColor("_Color", new Color(material.color.r, material.color.g, material.color.b, 0.4f));

}

}