There are a number of other APIs in the indices namespace that allow you to manage your elasticsearch indexes (add/remove templates, flush segments, close indexes, etc).

If you use an IDE with autocompletion, you should be able to easily explore the indices namespace by typing:

$client->indices()->

And perusing the list of available methods. Alternatively, browsing the \Elasticsearch\Namespaces\Indices.php file will show you the full list of available method calls (as well as parameter lists in the comments for each method).