In Wave.video, you can zoom in and out of video or image.
In order to zoom in/out, head over to the step Edit and switch to the tab "Video/Image" (depending on whether you have a video or an image as your background).
You can zoom in and out of the video/image by clicking the corresponding + and - signs in the video editing section on the right.
The smart algorithm will automatically create a palette of matching colors. You can always change the background color in the video editing section. Learn more about the video background here.
How to reset the image size?
Just click on the "Size" here: