Get a Taxonomy values in an array

You can retrieve a taxonomies terms with get_terms().

Via their docs:

$terms = get_terms( array(
    'taxonomy' => 'product_cat',
    'hide_empty' => false,
));

And it returns:

(array|int|WP_Error) List of WP_Term instances and their
children. Will return WP_Error, if any of $taxonomies do not exist.

Which you can view by doing somthing like

echo "<pre>".print_r($terms,true)."</pre>";