Lost phone

Did you enable Find My?

If you didn't turn on Find My [device] before your device was lost or stolen, it can't be used to locate your device nor you can use the IMEI number for tracking the device.

The best action would be to Change your Apple ID password and change the passwords for other internet accounts on your device. This can include email accounts, Facebook, or Twitter, etc...

The only specific protection plan that Apple offers is AppleCare+ with Theft and Loss

To check whether it is active or not, read this support article:--> Find information about your warranty or AppleCare plan - Apple Support

For all other types of insurance, please contact your insurance company.

Regards

Giulio

visit checkcoverage.apple.com to verify your coverage

Don'ts

If you remove the device from your account after you erase it, Activation Lock will be turned off. This allows another person to turn on and use your device.

Even if you have insurance it will become void if Find My was not enabled before the iPhone was lost

How would we know? Did you buy insurance?