When setting up WP Search with Algolia you will see various available content types to include with your Autocomplete configuration. Most of them are available post types, many are also going to be various taxonomies, and even users can be indexed.
However, one of the available post type based options is one labeled “All Posts”. This is a bit of a “shortcut” that will index and utilize all of the post types that are registered as searchable. If you’ve configured your search settings, this Autocomplete setting will use the same
If you’re only wanting specific post types to be considered for autocomplete, you should not also include “All Posts”.
Out of box, the Autocomplete template is going to show each content type in its own section. If you were to select “All Posts” as well as other individual post types at the same time, you’re going to be doubling up on content being indexed, as well as risk showing duplicate results in the different sections.
In short, if you want to have the widest search with the least amount of work, when it comes to post type content, use “All Posts”, however, if there are any that you don’t want to include, either set them to non-search able, or selectively choose which to include in your Autocomplete configuration.