text-scale-set
text-scale-set is an interactive autoloaded compiled Lisp function in `face-remap.el
'.
(text-scale-set LEVEL)
Set the scale factor of the default face in the current buffer to LEVEL.
If LEVEL is non-zero, `text-scale-mode' is enabled, otherwise it is disabled.
LEVEL is a number of steps, with 0 representing the default size.
Each step scales the height of the default face by the variable
`text-scale-mode-step' (a negative number decreases the height by
the same amount).