Please my new phone got lost before I got to open it. What can I do to get it back like track it? Can use serial number or the imei?

Serial number won't help. Since you did not yet have the phone set up with a carrier, the IMEI won't help either. Even if you did, the carrier would likely require a court order to track the phone.

Unfortunately, the only other way to track a phone is using Apple's Find My service, but the phone was not yet set up to use this option.

I'm afraid that there are no good answers for you other than checking with the Lost and Found at the metro.

I'm sorry, but at this point, there is virtually no chance of finding the phone.