Are there any parts that wear out in suspension which can be replaced to offer a softer more plush ride?

The ride isn't stiff, but softer wouldn't hurt

How old is everything? Had shocks replaced etc.

Some new shocks and standard height springs will make the car feel "softer" if the bump stops are worn, which they wear easily, the front of the car will bottom out quite a bit, however the bottoming out is more of an occurrence with a lowered car.

take 2 psi or so out of the tyres.

take 2 psi or so out of the tyres.

+1

If you have standard ride height, original wheels and tired suspension, go for 30 psi. Also look for new struts that are gas filled and have progressive rate dampening.
If you have lowered the car and have low profile tyres at 45 psi, not much you can do.

Car is stock height and as far as I can tell original suspension though it feels fine (if I press it down it doesn't oscillate and feels "firm"). Suspension maybe have been changed, it has a full log book from the Mitsubishi dealership but doesn't outline what was done pre 114,000km.
The tires as it is I have 29psi front 26psi rear as per the tire placard inside the door frame.

I am not sure whether new shocks would soften or stiffen the ride? I thought older shocks gave a softer ride. It does not bottom out nor bounce or skip off of bumps. Feels stable.

I thought that maybe some bushes go stiff or some parts dry out maybe?