I'm assuming you want them to be able to do this on-the-fly without affecting your master template. This is currently not possible. To do this, you'd have to let each user have their own copy of the template to adjust at will--not good for controling your form template (and potentially your data).

Sometimes, end-user need to modify the layout of the InfoPath template, such
as pagebreak, font size, etc. Is that possible to let end-user modify the
layout of InfoPath template?