There are 2 additional settings available in the Calcurates Magento 2 module config, that are responsible for the display of Delivery Dates info at checkout.

These Magento 2 settings affects how the Calcurates Delivery Dates feature will look at checkout.
The default Magento 2 date and time configuration defines how date and time will be displayed at checkout and the Calcurates Magento 2 extension follows these general settings. To set up date and time format in your Magento 2, on the Admin sidebar, go to Stores —> Settings —> Configuration and follow these steps:
- In the panel on the left, expand Catalog and click the Catalog subitem.
- Expand the Date & Time Custom Options section.
- To use a popup calendar as the input control for date fields, set Use JavaScript Calendar to Yes.
- To establish the Date Fields Order, clear the Use system value checkbox and set the order of each part of the date field as needed, using the day, month, and year variables.
- To set your preferred time format, clear the Use system value checkbox and set Time Format to one of the following: 12h AM/PM or 24h.
- To establish the Year Range for the drop-down values, enter the year (YYYY) to set the from and to dates. If blank, the field defaults to the current year.
When done with the configuration, click Save Config.