using System;

public class Program

{

    public static void Main()

    {

        var DateTimeMidnightFormat = "yyyy-MM-ddT00:00:00'Z'";

        var DateTimeFormat = "yyyy-MM-dd";

        var utcTime = DateTime.Parse("2020-07-05T23:50:50.000Z");

        Console.WriteLine(utcTime);

        Console.WriteLine(TimeZoneInfo.ConvertTimeFromUtc(utcTime.ToUniversalTime(), TimeZoneInfo.FindSystemTimeZoneById("Europe/London")).Date.ToString(DateTimeMidnightFormat));

        Console.WriteLine(TimeZoneInfo.ConvertTimeFromUtc(utcTime.ToUniversalTime(), TimeZoneInfo.FindSystemTimeZoneById("Europe/London")).Date.ToString(DateTimeFormat));

​

    }

}