There are third-party websites (such as swappa.com or imei.info ) that allow serial number lookups.
However, the system has limits. A serial number check confirms that a device is genuine, but it does not guarantee that all internal parts are original. A dishonest seller could replace a real logic board with a fake one while keeping the original outer casing and serial number sticker. Therefore, the serial number check should be combined with physical inspection and diagnostic software. Additionally, Apple does not provide a public database for checking ownership history beyond the Activation Lock status. check by serial number apple
The most reliable source for checking a serial number is Apple itself. There are third-party websites (such as swappa