Hi @Bluberry, very sorry to hear about what has happened.
We do not have any service that we can use to track your device based on your IMEI number, the only service that is available is the Google service called Find My Device.
This requires the device to be powered on and have an active Internet connection though, but you can also take a look at the links that @Strampke provided. The most important part, make sure to report it stolen to the police. When that is done, talk to your operator, so they can block the device from being used with a SIM card.