Could you please elaborate on "secure"?
Please note that the more "secure" the nginx configuration is, the less client would be able to access your website.
If you want to merely rise the rating of your configuration on SSLLabs, you could refer to the below topic.
https://community.letsencrypt.org/t/howto-a-with-all-100-s-on-ssl-labs-test-using-nginx-mainline-stable/55033/4
Thank you