Hello Richie,
I believe you would have to change a CSS style on the form in order to allow the width of your forms to change, if you have a permanent size that you'd rather have that is. Or you can add a control that can change the width of your individual form instance by typing in the value into a textbox.
Either way source code will have to be available to allow this functionality.
If this is something that you must have in your Dynamic Forms module we offer
Premium Support in which you can purchase hours from us and we can get this idea implemented. If you want to go this route I recommend filling out the appropriate form from this
LINK so we can develop a quote for you.
If you have any further questions please feel free to ask.
Thanks,
Ryan