using System;

using System.Text.Json;

using NodaTime;

using NodaTime.Serialization.SystemTextJson;

public class Program

{

    public static void Main()

    {

        var options = new JsonSerializerOptions().ConfigureForNodaTime(DateTimeZoneProviders.Tzdb);

        var serializedDate = JsonSerializer.Serialize(new LocalDate(2021,01,01), options);

​

        Console.WriteLine(serializedDate);

    }

}