using System;

public class Program

{

    public static void Main()

    {

        string dateStr = "2020-10-18T12:07:00.000-08:00";

​

        DateTimeOffset dto = DateTimeOffset.Parse(dateStr);

        Console.WriteLine("UTC:" +dto.UtcDateTime.ToString());

        Console.WriteLine("Offset time:" + dto.Offset);

        Console.WriteLine("Original string: " + dateStr);

        Console.WriteLine("dto toString:    " + dto.ToString("yyyy'-'MM'-'dd'T'HH':'mm':'ss.fffK"));

    }

}