using System;
using System.Text.Json;
public class Program
{
public static void Main()
dynamic w = new ExpandoObject() { Date = DateTime.Now, Item1 = 30 };
w.Item2 = 123;
Console.WriteLine(JsonSerializer.Serialize<dynamic>(w));
}
class ExpandoObject
public DateTimeOffset Date { get; set; }
public int Item1 { get; set; }
public int Item2 { get; set; }