Card Shape

main.dart

import 'package:flutter/material.dart';

void main() => runApp(
      MaterialApp(
        theme: ThemeData(
          useMaterial3: true,
          colorScheme: ColorScheme.fromSeed(seedColor: Colors.red)
              .copyWith(surface: Colors.pink),
          cardTheme: CardTheme(
            shape: RoundedRectangleBorder(
              borderRadius: BorderRadius.circular(4.0),
            ),
          ),
        ),
        debugShowCheckedModeBanner: false,
        home: Builder(
          builder: (context) => Scaffold(
            body: Center(
              child: Row(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  const Card(
                    child: SizedBox(
                      width: 100,
                      height: 100,
                    ),
                  ),
                  Card(
                    shape: (Theme.of(context).cardTheme.shape
                            as RoundedRectangleBorder)
                        .copyWith(
                      borderRadius: BorderRadius.circular(16.0),
                    ),
                    child: const SizedBox(
                      width: 100,
                      height: 100,
                    ),
                  ),
                ],
              ),
            ),
          ),
        ),
      ),
    );