Navigator push with/without fade animation

with fade

 Navigator.push(

  context,
  PageRouteBuilder(
    pageBuilder: (c, a1, a2) => Page2(),
    transitionsBuilder: (c, anim, a2, child) => FadeTransition(opacity: anim, child: child),
    transitionDuration: Duration(milliseconds: 2000),
  ),
);

without fade

Navigator.push(
    context,
    MaterialPageRoute(builder: (context) => const SecondRoute()),
  );