You needn't fill every inch of it. Is that a knee wall dying into the larger wall? Take some better pics, and do a couple from upstairs. Width and height dimensions would help, in a quick ketch. Upload all. in a comment box...this thread

I think there's something grand about it as it is. Plant has helpful height, a 'natural accent' where it is. A fab planter pot would be great, and what about a dress-up wood base too. [I might remove little table near the plant.]

Any idea about a rug - could anchor staircase with many little visuals.

Medium Size Green Peacock Talavera Ceramic Pot · More Info

Ok if you like chandelier's bronze to have metal... if fits with chest beyond [hand-carved?]

https://www.etsy.com/listing/689181105/xtra-large-solid-brass-planter-175w-x?gpla=1&gao=1&&utm_source=bing&utm_medium=cpc&utm_campaign=shopping_us_ps--home_and_living-power_seller&utm_custom1=k_c1a4d5bc14331b93666ab4d35bc64c58_k&utm_content=bing_412385671_1298523531504915_81157784660933_pla-4584757335754326:pla-4584757335754326_c__689181105&utm_custom2=412385671&msclkid=c1a4d5bc14331b93666ab4d35bc64c58a

This pretty detailed one popped up -

https://www.etsy.com/listing/1076915720/vintage-large-lion-paw-planter-large?ref=pla_similar_listing_bot-4

I think it looks great as is! I have become a minimalist in decorating. “Less is More”.

I agree - less is more. Keep the eyes on the main level - add a nice foyer rug, and focus first on decorating the foyer area. Consider a big, roundish chandelier to bring depth to the area.

How many angles/turns are in the staircase? it has a tower ascending vibe, and to me, unique enough to fill the stage.