Apple - Zoom in on photo in Quick Look on macOS Mojave
Is there any other new shortcut for zooming an image to actual size in Quick Look on the latest version of macOS Mojave?
In the public release of macOS Mojave 10.14, Command + 0 keyboard sequence appears to achieve the desired function.
To zoom back out again use the keyboard shortcut Command + 9.
You can use Command+ and Command- to Zoom in and Zoom Out, like you can do at Preview app.
In the beta, it was Control to actual size, Option to come back to fit in