How do I track my stolen iPhone 11 Pro?

The only way your Apple ID can be changed is if they know your previous password. Did you respond to a scam message claiming to be from Apple and gave the scammer your password?

With that information, they can take control of your device and you would not be able to do anything about it. You do need to contact your Cellular Provider to cancel your service and can also report it stolen to them where they may blacklist the device. It is also recommended to file a police report.

• Report it to local law enforcement. They might request the serial number of your iPhone or iPad, which you can find even if you don't have the device.
• Contact your wireless carrier to report your stolen iPhone. You should ask them to suspend your account, and file a claim if your iPhone is covered under your wireless carrier plan.

If your iPhone or iPad was stolen - Apple Support

samiryehia wrote:

I have no way to know the location of my phone, the thief has changed the Apple ID

You answered your own question ("How do I track my stolen iPhone 11 Pro?"). You don't. Find My was the only method available to you, and it's not available any longer.

Carriers can track phones by IMEI, but will not do so in the case of phones that are merely lost or stolen.