GIMP
Zoom in on the image
In GIMP, the + key will zoom in on the image. It is listed for Windows, and no Mac version is documented here.
Where it works: Image open
The plus key on a numeric keypad also zooms in. On a US English keyboard this character needs Shift and the equals key. The shortcut itself is unchanged.
Where this comes from
GIMP default accelerators - GNOME/gimp source
Documentation checked on 2026-09-14. That is a documentation review, not a test run inside the application.