Matt,

Check (info "(org) Export Settings")

and especially, the para near bottom:

When exporting sub-trees, special node properties can override the
above keywords.  These properties have an ‘EXPORT_’ prefix.  For
example, ‘DATE’ becomes, ‘EXPORT_DATE’ when used for a specific
sub-tree.  Except for ‘SETUPFILE’, all other keywords listed above have
an ‘EXPORT_’ equivalent.

HTH,

Chuck

> On Jul 21, 2021, at 11:52 AM, Matt Price <moptop99@gmail.com> wrote:
>
> Hi,
>
> I'm not sure if I'm reading the documentation properly, but my understnading is that I ought to be able to set export options as subtree properties, and that if I do so, they should be picked up by export engines when exporting subtrees.  However, that doesn't see to be happening for me, and from what I can tell, `org-export-get-environment` is not overriding global values when passed the `subtreep` parameter.
>
> I tried the following with emacs -Q , which seems to confirm my issue. Is this the expected behaviour, and if so, is there some other way for me to set subtree-level export options?
>
> --------------
> ** subtree
> :PROPERTIES:
> :SUBTITLE: testing
> :REVEAL_TITLE_SLIDE: nil
> :HTML_CONTAINER: section
> :END:
>
>
> #+begin_src emacs-lisp
> (let ((info (org-export-get-environment 'html t)))
>   (string-join `(,(plist-get info :subtitle) ,(plist-get info :html-container)) "\n")
>   )
> #+end_src
>
> #+RESULTS:
> :
> : div
> --------------------------
>
> thanks as always!