How do I track a lost iPhone using the IMEI number?

Apple does not participate here, and they do not have your IMEI. Your carrier has that, but you cannot track the iPhone with the IMEI. See this for a lost phone. Find your lost iPhone or iPad - Apple Support

We are not Apple. this is a user forum. You can not track the location using the IMEI. The only way to track it is using find my.

No. Apple does not track using IMEI.