Preheat the air fryer to 390°F for 3 minutes if the model recommends preheating.
Peel the sweet potatoes and cut them into uniform 3/4-inch cubes. Blot any surface moisture with a clean towel.
Toss the cubes with oil, salt, smoked paprika, garlic powder and pepper until each piece has a thin even coating.
Spread the cubes in one loose layer. Cook in two batches if they pile deeply or cover every opening.
Cook for 15 to 20 minutes, shaking at 6 and 12 minutes. Begin checking at 15 minutes.
Stop when several cut faces are browned and a knife slides into the centers with little resistance. Rest 2 minutes and toss with optional maple syrup.