settosize – Scale text to given width
The package defines a command
\set <text> \in <font> \to <size>
that chooses the “best” magstep that will fit the given text into the width, and typesets the text accordingly.
Maybe you are interested in the following packages as well.
- plnfss: Font selection for Plain TeX
- ofs: Macros for managing large font collections
- isf: Access italic computer modern sans in LaTeX 2.09
- smaller: Choose an "adjacent" size in LaTeX