Are you talking about the add-on? I don’t use it myself, but I think there should be a web-based UI with that information. There is usually a link on the add-on info page.
And you can go to the registry, which you can even download, but the IPs of the devices that are assigned do not appear.
Finally, the plugin says:
“his add-on provides a simple DHCP server for your network. It provides some basic needs, like, reserving IP addresses for your devices to ensure they always get assigned the same IP address.”
I do not believe Home Assistant has a DHCP Server.
There is probably a 3rd party custom integration or add-on that does this. In that case go to the github repo for that software and ask them. It is not related to HA any more than your browser has responsibility for the data that your email program provides.