The current expected behavior of Experience Builder is not to allow resizing of text for each interface format (i.e. PC, tablet and phone). Resizing the text in one of these interface formats will adjust it for all interfaces which is very clunky as those interfaces have different screen sizes and, therefore, require custom configuration of font size.
While customization of elements is allowed across the interfaces, text customization is not, which is a big shortcoming. So I strongly recommend that the next update of Experience Builder is improved to support the ability to configure text/font sizes within the text widget to adapt to different screen sizes.
