using System;

public class Program

{

    public static void Main()

    {

​

        var val3 = TimeZoneInfo.ConvertTimeFromUtc(new DateTime(2021, 10, 13, 18, 0, 0), TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time"));

        Console.WriteLine(val3.ToString("yyyy-MM-ddTHH:mm:sszzz"));

    }

}