Apple requires a 1024×1024 pixel app icon for App Store Connect. That single asset is used for the store listing; Xcode also needs smaller variants for devices (20pt to 1024pt in 1x, 2x, 3x).
iOS app icon dimensions (Asset Catalog)
Your AppIcon.appiconset includes sizes from 20×20 up to 1024×1024. Each size is used for different contexts (notification, settings, spotlight, app icon). Generating them manually is error-prone; use a tool that outputs the full set plus Contents.json.
Format and tips
Use PNG, no transparency for the 1024×1024 App Store icon (Apple may reject icons with alpha). Avoid rounded corners in the file—iOS applies the mask. Start with a sharp 1024×1024 or larger square image for best results.