To create a full-width parallax image we suggest using Page Builder by SiteOrigin.
Step 1: In the page builder editor, create a single column row, then click “Add Widget”.
Step 2: Find the widget you would like to display on top of the image (if you do not want a widget to display, you can simply add a blank text widget).
Step 3: Next, hover over the tool in the top right corner of the page builder row and select “Edit Row.”
Step 4: Under Row Styles click the Layout tab to open it.
Step 5: Set the Row Layout to Full Width Stretched. Here you can also add top and bottom padding to your image.
Step 7: Click the Design tab to open it. Here you can either upload a background image or select a background color. Then set background image style to Parallax.