Ultimate Addons for Elementor has several form styler widgets and recently added one for Fluent Forms. This Fluent Forms Styler widget has a lot of options including input field styling, title and description of the form, customization for radio & checkbox controls, different styles for error and success messages, typography, and other form elements.
The Fluent Forms team published a tutorial on how to use the Essential Addons form styler. If you own Essential Addons and are wondering about the integration then this tutorial shows how they work together. Fluent Forms currently has a 50% off sale on their lifetime package.