How to load native DLL based on platform in .NET core

using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Threading;
using System.Runtime;
using System.Reflection;

namespace NativeLibConsumeApp
{
    class Program
    {
        public delegate void CallBackDelegate(int a, int b);

        [DllImport("CallbackThreadSample.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern void GetData();
        [DllImport("CallbackThreadSample.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern void SetCallback(CallBackDelegate aCallback);
        static void Main(string[] args)
        {
            CallBackDelegate lTD = new CallBackDelegate(Program.Callback);
            SetCallback(lTD); //Sets up the callback
            int thread = Thread.CurrentThread.ManagedThreadId;
            GetData(); //This calls the callback in unmanaged code
           // while (true) ;
        }

        //Callback function which is called from the unmanaged code
        public static void Callback(int a, int b)
        {
            Console.WriteLine("A: {0} B: {1}", a, b);
            int thread = Thread.CurrentThread.ManagedThreadId;
        }
    }
}