Theme Horse

Hi Jack,

It would be better if you clarify in which section (post content image or for Single Page Background) you are seeking a parallax.
To make the Page background we can provide the Custom CSS code to make the Background image fixed when scrolling.(need to set Site Background First).
Or if for the Selective post/Page Single. You can use the Block Feature (Cover) for each Post/Page Single. To use Block feature you can click on plus icon (+) on top left or on the page section area and you can select the ‘cover’ under Media category. after then you will find various options to use on right side panel of post/page editor.

Thanks