Can I track my stolen iPhone 11 using IMEI when Find My iPhone is disabled?

No, you cannot track your phone with the IMEI number. Find My would have to be turned on before your phone was stolen and it cannot be done remotely. Also the thief cannot turn it off either if they do not have the Passcode to your device. It is not something that can be guessed before the phone automatically locks unless you were using something like "1234". There are scams where the thief will message you pretending to be from Apple to get your code.

The find my iphone has been disabled.

Not unless you disabled it yourself, or you were tricked into providing your Passcode, Apple ID and Password to someone else.

Maybe you are really saying that when you try to locate the phone using Find My, that you are seeing an "Offline" message?

Regarding your question about using the IMEI to try to locate the phone........your carrier can track the phone using the IMEI, but they will only do this in cases of an emergency.......like a missing person. Even then, the carrier will require a court order to start the process.