Animação 1

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Teste Animação',
      home: Animacao(),
    );
  }
}

class Animacao extends StatefulWidget {
  @override
  _AnimacaoState createState() => _AnimacaoState();
}

class _AnimacaoState extends State<Animacao> {
    double containerHeight = 150;
  double containerWidth = 150;


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Example'),
      ),
      body: Center(
        child: GestureDetector(
          onTap: () {
            setState((){
              containerHeight = containerHeight == 150 ? 250 : 150;
              containerWidth = containerWidth == 150 ? 250 : 150;
            });
          },
          child: Container(
            color: Colors.blue,
            height: containerHeight,
            width: containerWidth,
          ),
        ),
      ),
    );
  }
}