StaggeredAnimationInstantiation.dart

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      vsync: this,
      duration: const Duration(seconds: 5),
    );

    profileTopAnimation = Tween<double>(begin: -200.0, end: 0.0).animate(
      CurvedAnimation(
        parent: _controller,
        curve: const Interval(0.0, 0.125, curve: Curves.easeOut),
      ),
    );
    textOpacityAnimation = Tween<double>(begin: 0.0, end: 1.0).animate(
      CurvedAnimation(
        parent: _controller,
        curve: const Interval(0.125, 0.250, curve: Curves.easeIn),
      ),
    );
    profileMenuAnimation = Tween<double>(begin: -500.0, end: 0.0).animate(
      CurvedAnimation(
        parent: _controller,
        curve:
            const Interval(0.250, 0.375, curve: Curves.fastLinearToSlowEaseIn),
      ),
    );
    signOutBtnAnimation = Tween<double>(begin: 0.0, end: 1.0).animate(
      CurvedAnimation(
        parent: _controller,
        curve: const Interval(0.375, 0.500, curve: Curves.elasticOut),
      ),
    );

    _controller.addListener(() {
      setState(() {});
    });
    _controller.forward();
  }