That’s a good question. At the moment, Webflow’s forms are not customizable. However, you can integrate 3rd party forms into your site that allow some pretty cool custom features so your form data is nice and organized. Have you tried any form building software yet? (i.e. 8 Killer Web Form Builders for Your Site | Mashable)
If you have any trouble, don’t hesitate to let me know and I’ll do my best to help!