How to have an auto-complete field in my form?

Vorremmo creare un campo con autocompletamento dei comuni italiani ma jotform con permette di inserire tutte le scelte, infatti il numero dei comuni è 8092

I think that this widget will help you to achieve what you want, you will find the Auto-Complete widget on this link: http://widgets.jotform.com/widget/autocomp. 

This guide will help you to add the widget to your form: https://www.jotform.com/help/252-How-to-Add-a-Widget-to-your-Form. 

You will be able to add the list that you currently have, add it as you add the options in a drop down: 

Hope this helps.