Not always—it depends on the publisher for sure, and possibly the field (e.g., physics, chemistry).

In biology, you have several models for peer review. Completely blind reviews where both reviewers and authors are anonymized. You also have semi blind models where the reviewers know the identities of the authors, but the authors don’t know reviewers’ identities. You also have open reviews where everyone knows one another’s identities.

In completely blind and semi-blind models, you occasionally have reviewers that reveal their identity.