In a large pot of boiling salted water, cook the elbow macaroni according to package instructions until al dente. Drain and rinse under cold water to stop the cooking process. Set aside.
In a medium saucepan, place the eggs and cover with cold water. Bring to a boil. Once boiling, cover the pot and remove it from heat. Let it sit for 12 minutes. Then, transfer the eggs to an ice bath to cool. Once cooled, peel and chop the eggs.
In a large bowl, combine the mayonnaise, Dijon mustard, apple cider vinegar, garlic powder, onion powder, salt, and pepper. Mix until smooth and creamy.
To the dressing, add the cooked macaroni, hard-boiled eggs, green onions, sweet pickle relish, celery, and red bell pepper. Gently fold the mixture together until everything is evenly coated with the dressing.
Cover the bowl with plastic wrap and chill in the refrigerator for at least 30 minutes to allow the flavors to meld together.
Taste and adjust seasoning if necessary before serving. Garnish with extra sliced eggs or green onions if desired.