Some one put this up before. This is a plastic railing. Not wood. You could to some degree steam bend wood. Even this thick. But it would not be finished. Nor can you make that really tight horizontal bend. Plus to make bends like this with wood you require some serious pressure to convince the wood to move. And very stout forms to allow the shape to be made and set. Hundreds of pounds or kilos of force to bend wood of this cross section. That requires compression straps, long levers and clamps.

Mark