using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var sorted = new []

        {

            new { CreatedOn = new DateTime(2021, 11, 1), Supplier = "ABC" },

            new { CreatedOn = new DateTime(2021, 11, 2), Supplier = "XYZ" },

            new { CreatedOn = new DateTime(2021, 11, 15), Supplier = "ABC" },

            new { CreatedOn = new DateTime(2021, 11, 20), Supplier = "MNO" },

            new { CreatedOn = new DateTime(2021, 11, 25), Supplier = "ABC" },

        }

        .OrderByDescending(m => m.Supplier == "ABC")

        .ThenBy(x => x.CreatedOn);

        foreach (var item in sorted) Console.WriteLine($"{item.Supplier} | {item.CreatedOn:dd-MMM-yy}");

    }

}