EssentialHeaders is a focused WordPress plugin that attaches the HTTP security headers browsers expect, so protection is not left to chance or buried in server config.
Under Settings EssentialHeaders you get three tabs:
Headers covered:
Safer headers ship enabled with sensible defaults. CSP starts off so you can adopt it deliberately. Headers apply to public site responses (pages, feeds, and the login screen)—not wp-admin, AJAX, REST, GraphQL, JSON API, or XML-RPC. HSTS is only sent over HTTPS. Default HSTS uses max-age only; add includeSubDomains yourself when every subdomain is ready.