Find my phone

You cannot locate an iPhone by serial number or IMEI. You need to have previously enabled Find My iPhone on the device before you lost it.

If you know that you enabled Find My iPhone, log in to https://icloud.com/ and use the Find iPhone tool.

Unfortunately, you cannot locate an iPhone by IMEI or Serial Number. Local law enforcement, your carrier and Find My are your only options.

Do you have Find My enabled and access to your Apple ID?

Enable Lost Mode on the device as soon as possible by using the Find My app on another iPhone, iPad, Mac or Apple Watch connected to your Apple ID or from the Web (icloud.com/find).

You might also want to check out this Apple Support article.

Check this link...

If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support