and it requires OpenSSL 3.0, compiled with "enable-ktls" option.
Further, KTLS needs to be enabled in kernel, and in OpenSSL,
either via OpenSSL configuration file or with

  ssl_conf_command Options KTLS;

in nginx configuration.

To enable kernel TLS on FreeBSD 13 and above:

  # kldload ktls_ocf
  # sysctl kern.ipc.tls.enable=1

to load a software backend, see man ktls(4) for details.

Also, please visit the following link to get more details
https://hg.nginx.org/nginx/rev/65946a191197