Password
Settings → Privacy: enable and set a password. Visitors must enter it before seeing content; protected pages are never indexed.
Block-level locks
Lock a single link with a password, for subscribers only (opens after leaving an email) or as paid (opens after purchase).
Age gate
The Age gate block asks for 18+ (or any age) confirmation, remembered for 24 hours.
Sensitive content
Pages flagged sensitive show a warning first and their links become "nofollow". Publishing adult content without the flag violates the Terms.