Can I track my Apple Watch through my serial number , if so how do I do that ?

It is not possible to track any device by serial number. It might be possible to track by IMEI or SIM number but this is only available to your network, deep in the technical layers, nowhere near as reliable or accurate as the cop movies suggest, and usually only made available in extreme cases to Law Enforcement and similar authorities after appropriate legal compliance.

Because you cannot.

You cannot track any Apple device with serial number.