如何在类型扩展方法中实例化类型？

using System;

namespace MyExtensionMethods
{
    public static class StringExtensions
    {
        public static void PrintLength(this string str)
        {
            Console.WriteLine($"Length of the string: {str.Length}");
        }

        public static void CreateAndPrintPerson(this string name)
        {
            Person person = new Person(name);
            Console.WriteLine($"Person created: {person.Name}");
        }
    }

    public class Person
    {
        public string Name { get; }

        public Person(string name)
        {
            Name = name;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            string myString = "Hello, World!";
            myString.PrintLength();

            string personName = "John Doe";
            personName.CreateAndPrintPerson();
        }
    }
}