Sizing problem in leading icon on ListTile

main.dart

import 'package:flutter/material.dart';

void main() => runApp(const ListTileApp());

class ListTileApp extends StatelessWidget {
  const ListTileApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: const ListTileExample(),
    );
  }
}

class ListTileExample extends StatelessWidget {
  const ListTileExample({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('ListTile Sample')),
      body: ListView(
        children: <Widget>[
          ListTile(
            leading: DCheckbox(
              value: false,
            ),
            title: Text('Headline'),
            subtitle: Text('Supporting text'),
          ),
          Divider(height: 0),
          ListTile(
            leading: SizedBox(
              width: 64.0,
              height: 64.0,
              child: DCheckbox(
                value: false,
                size: 48.0,
              ),
            ),
            title: Text('Headline'),
            subtitle: Text(
                'Longer supporting text to demonstrate how the text wraps and how the leading and trailing widgets are centered vertically with the text.'),
          ),
          Divider(height: 0),
          ListTile(
            leading: DCheckbox(
              value: false,
              size: 64.0,
            ),
            title: Text(
              'A Very Big Headline',
              style: TextStyle(
                fontSize: 48.0,
              ),
            ),
          ),
          Divider(height: 0),
        ],
      ),
    );
  }
}

class DCheckbox extends StatefulWidget {
  final bool value;
  final double size;

  const DCheckbox({
    super.key,
    required this.value,
    this.size = 24.0,
  });

  @override
  State<DCheckbox> createState() => _DCheckboxState();
}

class _DCheckboxState extends State<DCheckbox> {
  bool isChecked = false;

  @override
  void initState() {
    isChecked = widget.value;
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    // return actualCheckbox();
    final containerSize = 40.0 * (widget.size / 24.0);
    return SizedBox(
      width: containerSize,
      height: containerSize,
      child: actualCheckbox(),
    );
  }

  Widget actualCheckbox() {
    return IconButton(
      onPressed: () {
        setState(() {
          isChecked = !isChecked;
        });
      },
      iconSize: widget.size,
      icon: Icon(
        isChecked ? Icons.check_rounded : Icons.circle_outlined,
      ),
    );
  }
}