That tiny sensor is better than you think—especially in good light. For portraits, step about 2 feet back from the keyboard; closer makes you look distorted, like a fish-eye lens. Use the Center Stage feature (if your Air is M1 or newer) to keep your face centered while you move around.
How to take a photo with MacBook Air - YouTube
Pair it with a ring light clipped to the screen for studio-quality selfies. No ring light? Tape a white sheet to the wall opposite the window—it bounces light onto your face. Cultural reference: This is essentially how 1970s Polaroid photographers worked, minus the cardboard backdrop.