Find IP address on stolen Mac

You can't. And there's no point. IP addresses are not unique nor permanent.

The IP addresses your Mac gets will depend on the network its connected to. Every time it connects to a network, wifi or wired, the router will issue an IP address to it. Normally it will be different each time.

Even if you knew the local IP address, there's nothing you can do with it. Its just an identifier for the local network, it has no bearing on the Macs actual identification or tracking.

Why do you need the IP address?

You can also use Find My Mac from your iCloud account. It will at least provide you the location where your Mac is. Unlike iOS I don't think you're able to erase the Macbook remotely however.

How can I find my IP address on a my stolen MacBook??

If your Mac is lost or stolen - Apple Support