Yes, you can allow your customers to add Extra Comments regarding the order. Here is how you can do so.
Login to Backend
Go to Stores ➤ Configurations ➤ AppJetty ➤ Delivery Date you will land on the “Configuration” page. Now scroll down to the Front End Configurations section and do the following configurations.
Label for delivery date comments: Enter the label for the delivery date comments.
Allow customers to add comments: Select Yes to allow the customers to add the comments
Make comments mandatory: Select Yes to make the comments mandatory for the customers.
After configurations click on the “Save Config” button to save them in Magento 2 order delivery date extension.