I would use at least one of the trim white colors. BM Simply White is a warm white, so I might be inclined to use that if you feel the Ultra White is too harsh.

I always like the the handrail to be slightly darker than the floor. In general this looks better for stained rails. In your case- either paint it darker and consider matching the iron as well so they don't compete with each other. OR you can consider a metallic paint for the whole system. https://www.modernmasters.com/landing/homeowners/brands/mpc

at the time I asked, this was the only pic you showed. I see a tiny bit of carpet. is that a bedroom? living room? what's in your kitchen? this same tile? I'm asking because when choosing a flooring out here, it should match the rest of the flooring in the other rooms. (carpet is fine for the bedroom) the second floor can be diff. It appears all of this carpet is worn and needs to be replaced, so what are you plans for flooring for the ENTIRE downstairs? Are you pulling up all of the carpet on the downstairs, around this staircase and other rooms? What about the kitchen? what's in there? is there a conncting family room? is it this carpet? is that staying? This is why I asked for pics. otherwise, just pic a neutral floor tile, say, a large format hex, or 24x24 type of tile

Dig a bit deeper. There are precast steps that look more natural like stone. https://www.edsconcrete.ca/steps-precast-stone You might be able to go over what you have. I don't like the fake gray stone on the retaining walls. It doesn't complement what little I can see of the house. I would select a minimal wrought iron handrail for this installation. You might be able to purchase it online and have it installed