Here is something I tried to draw for you that accents the modern Tudor feel of your house.

It has painted trim where you already have molding lines (can't match in my limited software, but use your imagination), a window in the big area above the garage--will give light and ventilation to any space, even if it is just storage, and opens up opportunity to convert later--a pergola across the garage, matching paint in the other gable (just paint out the vent) and more pillars and a brighter door to help emphasize the entry.

I feel the projecting gable visually looks unsupported and the span too large and adding a pillar would balance it out better. This was a popular detail in old Tudor Revivals BTW.

The pinkish beige color is a little hard to work with--I thought a mustard type yellow might work for the door (brighter than shown in picture) or an olive green or moss green, but it is hard to see the color of the brick and such. Maybe just a brighter version of the color you have would work. It will be tricky to get the color harmonies right--good idea to use one of the online paint programs, and compare colors in sunlight.

I did think about painting the pergola or maybe the siding of the garage a lightier color, like a light pinky beige or antique white, along with the pillars, door trim and perhaps the door itself, and the siding for the projecting gable above the entry. And maybe the "rafter tails" detail above the big window. I don't have time to do it digitally, but it is worth thinking about to give the house a little extra dimension without redoing the whole thing.

Just the decorative paint trim and some sort of decorative circular ironwork on the gable could do for now. Actually lowering the vent would defeat the purpose of the vent because it would draw air from the soffits and leave the hot air trapped in the peak of the roof. If you have ridge vents, then a gable vent isn't needed unless the gable is isolated from the rest of the roof.