You should use the Sitecore Forms Extensions for added feature. Like ShowFormPage, RawHTML, HiddenField… and more Here is the link for the Sitecore Forms Extension Check it out.
Category: Sitecore Form
BYTE Post 12 : How to change the html tags for Sitecore Form Elements
I wanted to change the form’s tags when you create the form elements. I wanted a div around certain element. The form csthl items are located in your [siteroot]\Views\FormBuilder\FieldTemplates Pick the item you want. You can change it there but better option is to create the same folder structure under Visual Studio project’s view. And…