Which of the following configurations is not possible in Form Builder?

In Form Builder, customizing field validation is not a supported configuration. Form Builder is primarily focused on simplifying the creation and layout of forms, allowing users to easily add layouts, nest them, and set layout formats directly through a user-friendly interface. The tool is designed to streamline the process of form development, but it typically handles validation through other means or configurations that fall outside of its direct capabilities.

Adding additional layouts is completely possible as it allows users to expand forms to fit complex data entry needs. Nesting layouts can also be achieved, enabling a structured design that organizes fields effectively. Similarly, setting layout formats is a key feature, allowing for a tailored presentation of the form. These functionalities are core to the operation of Form Builder, while field validation usually requires a different approach, often involving the use of business logic or rules defined elsewhere in the Pega platform.