Displaying a sign-up checkbox in your form is one of the great way to get more customers to subscribe to your newsletter. In this post, we'll show you how to add such kind of checkbox in Magento 2 forms with Blue Form Builder.
https://www.magezon.com/magento-2-form-builder.html

1. Open the edit page of a form that you've already created with Blue Form Builder. Then open Magezon Blue Form Builder section.
2. Open the window containing all elements by clicking on the plus icon on the top bar of the builder section, the plus icon at the bottom of an element on hover or the plus icon at the bottom of the builder section.
3. After that, find and click Subscribe element to add it the builder section.
4. In the element's settings popup, please pay attention to:
- Appearance tab: where you can add label, specify label position, etc. for the element.
- Advanced tab:
+ Required field: set the element to be required or not.
+ Checked by default: if Yes, the checkbox is automatically checked on page load.
+ Sub Label: enter additional information that is placed on the right of the checkbox.
+ Add field value to the Newsletter List: when filling the form, if your customers tick the
subscribe checkbox to agree to receive newsletters from your website, then the
newsletters will be sent to them through the values filled in the form fields you have
chosen. You can add multiple fields but remember that these fields must use Email
element.
+ Send Success Email: send an email to notify customers of successful subscription.
+ Need to Confirm: send an email to customers for confirmation.

Remember to save after you finish all settings.