How to try out new 'Search Builder'?
Note if you install from a tar file the extension is not available until 5.30. Git/composer/buildkit installs have it in 5.29.
Also the styling on the search page is messy until 5.31, and before then has some other issues.
UPDATE: As of 2020-10-06, it's now visible in the UI as an installable extension called &quot;Search Kit&quot; that comes included with 5.31+. You just install it like any other extension. For earlier than 5.31 see below.

Using user interface

In civi go to the menu for support - developer - api3 explorer.
Choose Extension with action Install.
For parameter pick Extension Key, and for the value put org.civicrm.search.
At the bottom click Execute.
Then the Search menu will have a new option at the bottom.

Using command line

cv api Extension.install keys=&quot;org.civicrm.search&quot;