I need to see pictures

Pics attached

“My architect/contractor says it is too late now and I should have told him earlier. But he never presented that as an option earlier.”

Too late for what?

The architect or the contractor?

What is shown on the drawings?

What do you mean by “Mediterranean?”

Too late to install casing without doing a lot of demo work on the sheet rock.

In my case the architect and contractor is the same.

The drawings don't have that level of detail. The contract included installation of casing, and I assumed it is doors and windows, but contractor now says it is only doors.

What I mean by "mediterranean" is not a very strict definition for the entire house. Just using it as a guiding theme for front door and the main living/kitchen/family rooms. Other rooms and even bathrooms are contemporary. So we have front door as wrought iron, high-ceilings and crown molding in living/kitchen/family and planning some more architectural molding like pillars. I was looking for casing primarily for living/kitchen/family rooms.

Is this what you mean?

Its not conventional nor ideal necessarily, but wood jamb extensions and casing can be installed over the sheetrock returns if there is enough window frame area. Just has to clear the hardware etc.

Nothing is ever "too late" per se, it may simply be too late to do it without additional costs. I'd agree with the architect from that perspective.

The style of windows shown in your photos look better in the four way wrap you currently have, IMHO.

What do you mean @Jazz Easy?

Drywall returns= hobo sheik. It’s cheap and looks cheap. It’s fashionable right now for some reason but it won’t be in a few years. Get wood casings and jambs. If you want a modern look, choose the casing style to match that

The clear lites over the combo's in your top photo seem a more contemporary or transitional style than Mediterranean. In my humble opinion, doing a sharp edge four-way plaster or stucco wrap will harmonize better. In your lower photo, I think adding interior casing will make the wall and hence room height look shorter under the soffit (slopped ceiling?). Interior casing windows generally adds a sense of weight to a room. But in the end, it is your home, and its what you want.