Heat oven to 350°F; spray 9x13-inch dish and spread 1/2 cup enchilada sauce in bottom.
Thoroughly mix turkey, 1/2 cup sauce, sour cream, 1 cup cheese, chiles, onion, cumin, garlic powder, salt, and pepper in large bowl.
Wrap tortillas in damp paper towel; microwave 30 seconds to soften for rolling.
Put about 1/2 cup filling down each center; tightly roll and place seam-side down in dish.
Pour remaining sauce over, covering all enchiladas.
Scatter remaining 1 cup cheese evenly over.
Cover with foil; bake 20 minutes. Uncover; bake 5 minutes more until cheese bubbling and starting to brown.
Cool 5 minutes; optionally top with cilantro, avocado, and lime juice. Serve with extra sour cream.