Dropdown is a common field of a form that lets customers select an option from a list. And in this post, we'll show you how to create a dropdown field in Blue Form Builder, a simple and powerful Magento 2 form builder extension.
https://www.magezon.com/magento-2-form-builder.html

1. In the edit page of a form, open Magezon Blue Form Builder section. Click the plus icon in the top bar, at the bottom of an element or at the bottom of the builder section to open the popup containing all elements.
2. Find Select element and click to add it to the builder section. After the element is added, a popup containing its settings will appear.
- Appearance tab: where you specify label, label position, etc. for the element.
- Options tab: where you specify options listed in the dropdown. Tick the Default checkbox of the option that you want to be automatically selected. Click the recycle bin icon to delete the option.
- Advanced tab: turn on Shuffle Options to arrange the options randomly. Turn on Show Others Option to add another option to the dropdown that allows customers enter their answer in a text area. You can specify Others Label [/b]and [b]Others Description.

Remember to save after you finish all needed settings.