By the useful method of reading a review article, I have found out that I fortunately was wrong about Pages for iPad: it does have options for changing font and the size of text. It was indeed almost too incredible to believe that it didn't, and I would not have believed it, if not for Apple's very occasional incredible choices, for example a mouse cord too short to reach around to the other side of a laptop and still be useable!
So, this is apparently the downside of the no-menu interface of a tablet (which has many positives)*. When you have many options, how do you present them without stealing too much screen space? In this case, I think Apple was too clever by far... a little button has a little "i" on it. This is normally "information", but in this case it serves up the various Styles possible for the text.
This is odd enough in itself, but then the pop-up menu with styles has no indication that it actually scrolls down to more options. It looks finished, no scroll bar or arrow or anything. But it does actually scroll, and when you do that, you find "text options" right at the bottom, which let you set text size, color, and font. That is very well hidden for options which normally is the very first thing you want to use when you set up a word processing document. Sigh.
* Well, all right, it actually does have menus, which make anything possible, the problem is, like we can see here, that there is not yet a standard way of presenting these menus, so the user can figure them out.