HSTS Missing From HTTPS Server (RFC 6797)

Hello. We’re trying to configure security settings on our site. The audit says, “HSTS Missing From HTTPS Server (RFC 6797)”. According to this article, we are supposed to be able to enable this option via Site settings > Publishing tab > Advanced publishing options . However, these settings are nowhere to be found. Please help!

From what I can see, HSTS may only be available on Enterprise plans.
This note is at the top of the page you linked;

Also see this post;

And this wishlist item;