How to verify authenticity of an Apple Charger using its serial number?

no, the serial number is useless for this it's not some magic number, anyone can get hold of a valid serial number and add it to their faked device

how to check if my iphone adapter fake or… - Apple Community

If you purchase this power adapter directly from Apple or an Apple Authorized Reseller, then it is an original Apple device. If not, then it could be a fake. Apple does not provide a means to verify their power adapters by serial number.