How to get all taxonomies which can be added in menu?

The taxonomies visible in the admin menu are exactly those taxonomies that were registered with show_in_menu = true and show_ui = true. For a reference on this, see the documentation on register_taxonomy, the function for adding (custom) taxonomies.

To query these taxonomies, use the corresponding parameters in get_taxonomies:

get_taxonomies( array(
    'show_ui' => true,
    'show_in_menu' => true,
) );