depends on your style and preferences

I never ever repeat fabrics on my pillows(unless it's pillowcases and shams for a bed)

other people always do. yet others mix-repeat some, do 2 different pairs for example.

there's no set rule for that.

what look usually speaks to you? do you prefer symmetry? do you love soft or strong contrast? what's your tolerance to pattern? many colors-do they make you happy and calm, or the opposite, overwhelmed?

Can you post photos of the couch and carpet?
"Solid neutral" could be light tan or off white......"

Carpet color photo... perhaps there are here and I don't see them.

I prefer to mix prints, but with some symmetry.

If I had a loveseat, I'd do a similar arrangement of two pairs of matching pillows and a fifth pillow that's different. I wouldn't necessarily choose the same pillows as those on the sofa for the loveseat, but would look for similar/complementary colors and patterns.

I probably have more pillows on my sofa than many people would want; however, it speaks comfort to me. (Also, I think a cat must've smooshed them some before I took the photo above. They usually sit up a little taller than this. ;-))

boy, thought we would never get to the pillows.

a little modern alien? or some simple gold.

I like to mix color and texture so I would do two on each side of the sofas but maybe two different patterns or materials.

Picture of the room would help but here are some suggestions on some pillows that might help bring out the color in the room.

cmon ljay watcha say?