Starting from version 2.11.0, the delivery date format on the frontend is displayed according to the selected store locale in Magento configurations: Stores → Configuration → General → General → Locale Options → Locale.
For lower versions, the format of the delivery date is MM/DD/YYYY by default. It can't be changed in the extension settings, but it's easily done through the code changes. For that, please follow the steps below.
Step 1. Open the GiftCard/view/frontend/web/template/datepicker.html
file, scroll down to line 22 (starting with data-bind=), and replace the placeholder with the desired one:
The result should be as follows:
This doesn't change the date format yet — only the "example" your customers see in the date picker widget
Step 2. Open the GiftCard/view/frontend/web/js/datepicker.js
file, scroll down to line 38 (changeYear: true), and add a new line after it. Paste the following, comma included:
dateFormat: 'dd/mm/yyyy',
Now, the date will show in the desired format on the storefront:
Additionally, you can change the date display in the mini-cart and checkout, if the Show Gift Card Options in Mini Cart And Checkout setting is enabled. For that, open the GiftCard/Model/GiftCard/Product/Type/GiftCard.php
file and find lines 276-277.
These lines are to be replaced with the code snippet below:
$chosenDate = \DateTime::createFromFormat(
'd/m/Y',
$buyRequest->getData($field),
new \DateTimeZone($buyRequest->getData(GiftCardOptionInterface::DELIVERY_TIMEZONE))
)->getTimestamp();
The date will then be recognized correctly in the product details in the shopping cart, preventing any discrepancies in case of a date shift due to the timezone difference.