如何在showDatePicker中调整文本initialDate的大小

import 'package:flutter/material.dart';

class MyDatePicker extends StatefulWidget {
  @override
  _MyDatePickerState createState() => _MyDatePickerState();
}

class _MyDatePickerState extends State<MyDatePicker> {
  TextEditingController _dateController = TextEditingController();

  Future<void> _selectDate(BuildContext context) async {
    final DateTime? picked = await showDatePicker(
      context: context,
      initialDate: DateTime.now(),
      firstDate: DateTime(2000),
      lastDate: DateTime(2100),
    );

    if (picked != null) {
      setState(() {
        _dateController.text = picked.toString();
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Date Picker'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            ElevatedButton(
              onPressed: () => _selectDate(context),
              child: Text('Select Date'),
            ),
            SizedBox(height: 20),
            TextFormField(
              controller: _dateController,
              style: TextStyle(fontSize: 20), // 调整文本大小
              decoration: InputDecoration(
                labelText: 'Selected Date',
              ),
              readOnly: true,
            ),
          ],
        ),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: MyDatePicker(),
  ));
}