No Brian it does not. You can purchase responsive themes for wfb.

The breakpoints would be set in RLM.
I had assumed you were adding the form to a RLM layout

Brian, have you tried adding it with the script instead of an Iframe?
That way you don't have to worry about the bottom getting cut off. Drop it into a <div> or col span to hold it in place and you're done:

You don't need to worry about break-points with the responsive forms.

For adding it to a page, I have only used the prescribed code from FB shown in the window when it finishes an export.

Sorry Brian, I thought you were using an Iframe on the page to display the form. The only time I've come across your issue was when trying to display an SDrive form through an Iframe. In that case I had to find the max height of the form and specify that in the Iframe code. I didn't put any other elements under the form so it wouldn't cover anything up when it went to one long col at phone size.

I just haven't come across that problem when using the manual export js snippet.