icon_padding.dart

import 'package:flutter/material.dart';

final Color darkBlue = Color.fromARGB(255, 18, 32, 47);

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: MyWidget(),
        ),
      ),
    );
  }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
        decoration: BoxDecoration(
            shape: BoxShape.circle,
            border: Border.all(color: Colors.white, width: 2.0)),
        child: IconButton(onPressed: () {}, icon: Icon(Icons.add), padding: EdgeInsets.all(0)));
  }
}