Where to find ‘catalog/shipping/estimate’ value?

I have a estaminated shipping time shown in product view as a String. As Im new in this magento solution I cannot get around where this “1-4 Liefertage” string is created (or calculated).

I found the function responsible:

/**
 * Get store config value
 *
 * @return string
 */
public function getProductShippingEstimateLabel($storeId = null)
{
    return $this->scopeConfig->getValue(self::PRODUCT_SHIPPING_ESTIMATE, ScopeInterface::SCOPE_STORE, $storeId);
    // return $this->scopeConfig->getValue('catalog/shipping/estimate','store',null);
}

And I found the ScopeConfigInterface.php Interface. Parameters for getValue() are ‘catalog/shipping/estimate’ and ‘store’, $storeId is null.

I found also the Shipping Estaminate Label in Magento Admin Backend, but its empty, so I guess it gets overridden by an external module or similar? Also changing the Label in the Admin Backend was leading to nothing, as it stays empty. Flushing of the cache and so on didnt helped to take effect changes.

Where is the missing link? getValue() is in the Interface well defined. Its part of Magento:

/**
 * Retrieve config value by path and scope.
 *
 * @param string $path The path through the tree of configuration values, e.g., 'general/store_information/name'
 * @param string $scopeType The scope to use to determine config value, e.g., 'store' or 'default'
 * @param null|int|string $scopeCode
 * @return mixed
 */
public function getValue($path, $scopeType = ScopeConfigInterface::SCOPE_TYPE_DEFAULT, $scopeCode = null);

Where does: ‘catalog/shipping/estimate’ refer to in the Magento Environment. Where can I proceed my investigation where “1-4 Liefertage” is eventually created..

I need to replace this term dynamically and on more advanced business logic.

Thanks in advance and Regards.