https://bugs.openldap.org/show_bug.cgi?id=9313
--- Comment #1 from Michael Ströder michael@stroeder.com --- This is rather an usage question and thus it's better to post this on the openldap-technical mailing list:
https://lists.openldap.org/postorius/lists/openldap-technical.openldap.org/
Yes, recent versions of OpenLDAP support TLSv1.3 but this also depends on crypto library (OpenSSL or GNUTLS) and version used.