We recently added the ability to Zoom when using the Paint tools such as the Paint Brush, Shapes Tool, Spray Tool and Eraser.
When you have the paint tool selected, you will see the Zoom slider at the bottom of the tools panel.
Move the slider to the right to increase the magnification for the page. Move the slider to the left to return to the normal size (100%).
Primary Theme -
If you do not see the Zoom control when a paint tool is selected, make sure the setting is set to "Yes" on the Settings page.
Click your account icon and choose Settings.
Make sure Allow Zoom is set to Yes.
You can find out more about the recent update to Wixie here