Xfce entered zoom mode. How do I exit?

Alt+scrollwheel.

So in my case I had pressed alt+two fingers on mouse pad.

To Turn on or Turn off Zoom, you may use Alt+Windows+8

This zoom mode is traditionally bound to Ctrl+Alt+Keypad + to zoom in and Ctrl+Alt+Keypad - to zoom out. These keys are not available if the DontZoom option is set in the ServerFlags section of /etc/X11/xorg.conf.

This feature is operated by the server, I don't know how to set it from a client. The xrandr command may influence it with its --scale option, or some other option may be able to reset the zoom setting; I'm unfamiliar with the interactions between the old-time server zoom and the modern RandR support.