You don't need to edit a specific theme individually.
The solution was different and it's gtkrc in the home directory.
For your convenience, a simple plugin that will do this and allow you to further edit the size of all other icons.
In menu: Windows/Change menu letters & other icons...
Only tested for Windows and Gimp-2.10.22 (gimp.org and portable Samj).

Thanks!

Awesome MareroQ! Perfect! Works on my GIMP 2.8.10 as well. Thanks! Makes a world of difference for these old eyes.

Hi Gimp users

I add the "Change menu & icons" plugins to my GIMP AppImage on Linux O.S Inside ChromeBook !!
And it is working very good.

Thanks Thanks Thanks .....

Doron

It works with windows 10 64 Bit in Gimp 2.10.36.

Not all themes work with this plugin. The themes that don't work are the Clearlooks Gimp 2.10 Color Hinted Themes. They throw an error when trying to load them and the font size doesn't fit the navigation bar.

Unfortunately, Clearlooks themes no longer work well for the latest versions of Gimp 2.10 - you can report this to the author (migf1).
Clearlooks also stretches the menu a lot.



Using the 'Change menu & icons.py' plugin will not change this.