Many CAD designs or models (including .stp files - STEP format) can be simply exported as plain images (like JPEG/PNG), mostly for previewing purposes. Such stp to jpg conversion or export can be typically done with some kind of image export function that should be available in plenty of CAD programs. In most cases this is done for purely preview purposes only.
Open STP file Open JPG fileA 3D product data optimalization software
A 3D CAD translation software