Get Advanced Custom Field Options by Site ID in WordPress Multisite

Out of the box, Advanced Custom Fields offers immense power but provides no functions to work with WordPress Multisite sites. Fortunately, WordPress makes it easy to work with multisite sites.

Throw the following function into your theme functions.php file and call it at will. Just provide the field name and site ID, the function will get your value from that site (if there is a value and field exists).

function get_acf_site_option($field_name, $site_id) {
    switch_to_blog($site_id);
  
    $value = get_field($field_name, 'option');
  
    restore_current_blog();
  
    return $value ? $value : null;
}