Latex submission template: keep figures to margin size?
I strongly advise complying with the formatting guidelines that you are provided.

Organizations like Elsevier give you a template an submission instructions for a reason, and in many cases the final formatted version will look nearly identical to a submission that follows their template. You can push your luck by violating the formatting guidelines, but this will make you look unprofessional and may annoy the editor and reviewers.  Do you really want to take that risk?

More to the point: most visual material can be readily organized into a number of formats.  Are you certain that you must have massive landscape images?