XenForo Enhanced Search is an add-on that replaces the built-in XenForo search system and is built to take advantage of Elasticsearch to provide a higher performing and more flexible search system for XenForo.
Configuration
Once installed, XenForo Enhanced Search is configured via Setup > Enhanced Search in the admin control panel.

Initially, you will need to enter the details of your Elasticsearch server. Once you have entered the Elasticsearch details, you will be able to configure elements about your index:

• Stop words: stop words allow you to control whether any words won't be included in the index. This can reduce the size of the index.
• Word stemming: if enabled, this can improve results by considering different forms of the root word to be identical. For example, searching for "tests" would also match "test", "testing" and "tested".
• Accent removal and character simplification: if enabled, accents and other characters will be simplified before indexing. This can improve results by allowing you to match a word (such as esta/está), regardless of whether the post or the search included the accent.