There are three ways to search rows in Dataverse. Relevance Search, Quick Find (single-table or multi-table) and Advanced Find. Quick Find (multi-table) is also called categorized search.
With Relevance search turned on you will get access to the latest search features such as easily access to a global search field, auto complete as you type a user friendly result page and more.
There is also a Relevance search API from Microsoft.
New feature is coming!
In 2021 Release Wave 1 Release Plan a new feature is presented: Use Relevance search in your Power Automate cloud flows! Search records in Microsoft Dataverse using relevance search