using System;

using System.Text.Json;

using System.Text.Json.Serialization;

public class Program

{

    public static void Main()

    {

        var json = "{ \"password_expiry_date_time\": \"2030-10-08T00:20:01+00\" }";

        var test = JsonSerializer.Deserialize<Test>(json);

        Console.WriteLine(test.PasswordExpiryDateTime);

    }

}

​

public class Test

{

    [JsonPropertyName("password_expiry_date_time")]

    public DateTimeOffset PasswordExpiryDateTime { get; set; }

}