Not exactly. You can have an email address that's the same as a nip05, you can run a relay and email server on the same machine. But they're different technologies.
Discussion
Technically, you don’t even need to run an email server or a relay. Just get a domain and connect it to Google Workspace to get custom email. And create a NIP-05 on the same domain
If you wanna get kyc'ed and pay Google to read your emails, that is.
I use Mailcow dockerized on an Ubuntu server VM on my local network.
I also use MXRoute.com for a few domains. $50/year for unlimited domains and email addresses, but only 50gb storage shared.