How do I scale all font faces in emacs?

[Matt Young]

Hello - I find myself needing to enlarge text in emacs in order to be
able to read it. I've been able to enlarge only some text by using
``set-frame-font'' in my emacs configuration, but I notice that other
faces are not affected by this. For instance, the mode line, and what I
think is eldoc in the minibuffer is not any larger. Some modes define
their own face settings as well that seem to ignore the more global
settings. 

I am not an emacs configuration expert and I am not sure that I am even
using the correct terminology or what options are even available in
this area.

Using ``customize-font-face'' is not a solution because there are over
600 entries there and I don't know what any of them control, and I do
not feel I should have to configure a multitude of faces individually.

Is there any way to scale all text globally with a single setting so
that it affects every face at once?

If there is not, I feel this could be worth a bug report. It is
important that something like this is as easy as possible for users
with vision problems.

Thank you