Seating flexibility is all about clever stuff that makes the car more comfortable and practical. The C3 doesn’t really do much of either, to be honest.
The front passenger doesn’t get seat-height adjustment or adjustable lumbar support, only the usual manual forward and aft movement, and backrest recline.
It’s the same in the rear. Unlike a Honda Jazz, which offers all sorts of seating combinations to help prioritise between carrying luggage or passengers, the C3 just comes with folding rear seat backs, split in a 60/40 arrangement.