Thank you for reaching out and posting this question!
I understand you're looking to add an extra line of text to the Newsletter section in your footer. Yes, it is possible to add an additional line under the current heading of the Newsletter section and, since you're using the Debut theme, then this is something that our Theme Support can help you with. It's important to note that while your store will need to be subscribed to a plan in order to be eligible for customization support; however, you'll be eligible to use the complimentary design time included with the subscription for customizing your theme. While we’re not able to provide account-specific support via the Shopify Community at this time, we’d be happy to continue assisting you through live chat, email, or callback. Please visit the Shopify Help Center and log in to your account to create a support request.
If you have any other questions on this topic, don't hesitate to let me know!
Elias | Social Care @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog