Question

What happens if you view a new HTML5 form input type in an older browser

Answer 1

it will suggest to use a newer version of browser

Answer 2

When you view a new HTML5 form input type in an older browser, most of the browsers both old and the new can handle the HTML elements even they are unrecognized as input elements.

But as a user, you can make the browser to identify and handle those input types. Few old browsers ignore the new elements, hence you need to add a rule to the web page to behave like block elements.