I think one way to solve this is to “add new page” in a site and then use something like Blocks Plus to achieve the desired result.
But at least for this particular use case, I want to inquire about a more direct way.
Inside the theme (/themes/theme/view/omeka/site/item, there is a search.phtml page. It is more or less a shell that loads the “partial” (common/advanced-search).
I have a need to create a different search form (probably several actually), and I already have a partial (common/advanced-search/properties-codex) that exists.
I was hoping I could just copy search.phtml to a new file (e.g. codex.phtml), modify that shell to point to the new partial, and be able to call it as a URL (/item/codex rather than /item/search). Of course, it generates a route error (“Not found” - “Reason: error-controller-cannot-dispatch”) because the Omeka-S application doesn’t know about it yet.
When I look inside /application/config/routes.config.php, I see lots of stuff regarding controllers and routes. I am not a master of this yet, but have learned enough over the past 3 years. But what I do not find when I search in the text editor is anything for “item” or for “search”. It appears most of the other routes (what you would see/call in the URL) are there, but not these - so I’m guessing they are somewhere more “core” Or are handled in some other way.
Hoping there is a quick hack / direct way to enable Omeka to recognize that when I type /item/codex, I want it to load /themes/theme/view/omeka/site/item/codex.phtml.