Yes you can. You file what's colloquially known as a "John Doe lawsuit", then serve a subpoena to a third party (such as Namecheap) to obtain that information.

Yes you can. You file what's colloquially known as a "John Doe lawsuit", then serve a subpoena to a third party (such as Namecheap) to obtain that information. You then have the information to amend the pleading and proceed against that party.