On Sat, Nov 06, 2021 at 06:48:00PM +0100, fatiparty@tutanota.com wrote:
> Nov 6, 2021, 16:30 by tomas@tuxteam.de:
> 
> > On Sat, Nov 06, 2021 at 04:55:45PM +0100, fatiparty--- via Users list for the GNU Emacs text editor wrote:
> >
> >>
> >> Nov 6, 2021, 15:40 by daniel.herzig@outlook.at:
> >>
> >> >
> >> > Increasing and decreasing font size works for me (emacs 27.x.y [at least since 26] on pure Debian, Raspbian,  Guix, and  Windows 10)   using the built-in keybindings ‚ ~C-x C-+~, and ~C-x C--~, respectively.  I haven’t had a look though which functions are called by these bindings.

[
...]
> The problem is related to having the following call
> 
> (setq text-scale-mode-step 1.0)

Well, this is telling Emacs that the fonts are to be
scaled by a factor 1.0 at each step, i.e. leaves them
unchanged. So it is working as it should :-)

The default value is 1.2, which makes somewhat more
sense. Try another value (I guess you want something
greater than 1).

Cheers
 - t