No, it is only for ones that have pea combs, which were created from Ameraucana (sometimes Araucana) stock. Hatcheries have been producing these EEs for decades... long before the Ameraucana was accepted into the Standard of Perfection as a breed. EEs are almost a breed in themselves, but you can think of them as non standard Ameraucanas. The name Easter Egger originated with some hatchery to market this "breed" but today the term is also being used to describe any cross that ends up having a gene for blue shells. To me this can get a bit confusing. I think of EEs as hatchery birds with pea combs. They aren't really crosses, the hatcheries have bred them fairly consistently over the years. I got my first ones 30 years ago.
By contrast, Legbar crosses will likely not have pea combs, but the blue shell gene that they carry did originally come from pea-combed Ameraucana or Araucana birds.
And that's more than you probably wanted to know!