code: public function createSetting($key, $value)
      {
          $parameters = [
              'query' => [],
              'body' => json_encode(['key' => $key, 'value' => $value], JSON_UNESCAPED_UNICODE),
              'headers' => [],
          ];
  
          $result = $this->post('v1/accounts/settings', $parameters);
  
          return $result;
      }
docs: Creates a new setting.
  
  Creates a new, previously not existing setting.
  
  @param string $key   The key (identifier) of the setting
  @param string $value The value of the setting