Try this:

    BoxCollider b = obj.GetComponent<BoxCollider>(); //retrieves the Box Collider of the GameObject called obj
    
    vertice1 = myobject.transform.TransformPoint(b.center + new Vector3(-b.size.x, -b.size.y, -b.size.z)*0.5f);
    vertice2 = myobject.transform.TransformPoint(b.center + new Vector3(b.size.x, -b.size.y, -b.size.z)*0.5f);
    vertice3 = myobject.transform.TransformPoint(b.center + new Vector3(b.size.x, -b.size.y, b.size.z)*0.5f);
    vertice4 = myobject.transform.TransformPoint(b.center + new Vector3(-b.size.x, -b.size.y, b.size.z)*0.5f);
    vertice5 = myobject.transform.TransformPoint(b.center + new Vector3(-b.size.x, b.size.y, -b.size.z)*0.5f);
    vertice6 = myobject.transform.TransformPoint(b.center + new Vector3(b.size.x, b.size.y, -b.size.z)*0.5f);
    vertice7 = myobject.transform.TransformPoint(b.center + new Vector3(b.size.x, b.size.y, b.size.z)*0.5f);
    vertice8 = myobject.transform.TransformPoint(b.center + new Vector3(-b.size.x, b.size.y, b.size.z)*0.5f);

Try this:

    BoxCollider b = obj.GetComponent<BoxCollider>(); //retrieves the Box Collider of the GameObject called obj
    
    Vector3 vertice1 = myobject.transform.TransformPoint(b.center + new Vector3(-b.size.x, -b.size.y, -b.size.z)*0.5f);
    Vector3 vertice2 = myobject.transform.TransformPoint(b.center + new Vector3(b.size.x, -b.size.y, -b.size.z)*0.5f);
    Vector3 vertice3 = myobject.transform.TransformPoint(b.center + new Vector3(b.size.x, -b.size.y, b.size.z)*0.5f);
    Vector3 vertice4 = myobject.transform.TransformPoint(b.center + new Vector3(-b.size.x, -b.size.y, b.size.z)*0.5f);
    Vector3 vertice5 = myobject.transform.TransformPoint(b.center + new Vector3(-b.size.x, b.size.y, -b.size.z)*0.5f);
    Vector3 vertice6 = myobject.transform.TransformPoint(b.center + new Vector3(b.size.x, b.size.y, -b.size.z)*0.5f);
    Vector3 vertice7 = myobject.transform.TransformPoint(b.center + new Vector3(b.size.x, b.size.y, b.size.z)*0.5f);
    Vector3 vertice8 = myobject.transform.TransformPoint(b.center + new Vector3(-b.size.x, b.size.y, b.size.z)*0.5f);