Can I track my iPhone 6s with IMEI number?

As a practical matter, your phone is gone. Most stolen phones are not recovered.

You can try to make the phone less valuable to the thief or fence.

• If you had Find My enabled, you can mark the phone as Lost, and optionally request a remote Erase.
• You can also report the phone as stolen to the police and to your carrier, and ask the carrier to blacklist the phone. If they do, then barring your recovery of the phone, no carrier who honors that blacklist will provide cellular phone, text message, or data service to that phone ever again.

If your iPhone or iPad was stolen - Apple Support

Do's and Don'ts for lost iPhones - Switched Off - Offline - Beware of Phishing – Apple Community

Note that if you were using Find My, and it shows you a location, you should not go to confront criminal(s) in person. You might lose a lot more than just a phone.

No. A normal user cannot track an iPhone with just IMEI.