Without proper documentation I'm unsure what are the features supported by the search. I'd like to have bolean keywords in the title only or also in the body, filter by categories and by users, sort by date and number of replies.
Advanced discussion search
bavard it's true that there isn't much documentation.
There also aren't many advanced search options.
The sorting options are those available via the UI.
There are some search gambits that are not documented. I listed most of them here https://discuss.flarum.org/d/21821-documentation-of-all-search-functions
Some extensions might also add their own gambits.