Umbrella stand with art above? Or maybe a tall, narrow plant.

It's a small enough area in a traffic pattern so you could leave it as is, but if you'd like to add something I would suggest an orchid in a nice vase like a blue/white Chinoiserie vase on a tall plant stand or a non-breakable alternative vase if you have kids.

Or a hall tree if you never have enough entry closet space for guests.

I'd not put anything there that could be caught with someones toe and knocked over, breaking the toe or the object that hits the floor.

If you hate the plain, you could add wainscoting on just these two walls; then above that,

... You could add wall paper and/or

... Paint the corner a different corner and make this corner a pair of accent walls and/or

.... You could add mirrored tiles.

Some combination of these four ideas might work but, unless carefully planned, you could end up making the corner cluttered looking.

Another possibility is adding a modern corner wall shelf that is affixed to the wall to provide an opportunity display something unbreakable (or at least not highly breakable since catching something with an elbow would be a possibility).

https://www.atgstores.com/shelves-display-ledges/4d-concepts-hanging-corner-wall-mounted-storage-shelf_4885345.html?af=2615&ef_id=V13rdQAABKMhIoO2:20160612230837:s

Another option would be to connect the two corner with an angled wall and create shelving behind the angled wall accessible from the closet on the right. A mirror or clock on the wall would work well or perhaps even a wall hanging hat rack.

https://signaturethings.com/content/images/thumbs/0000328_24-wall-mount-coat-rack.gif

This, or a column made like the ones you already have topped with an arrangement.

I like the idea of using triangular shelves and some sort of molding to make it look like a built-in...

some decorative hooks for guest coats or your bag. A bag of things that need to go up stairs. Get something pretty and useful.

I like the idea of using it for shelves, or you could put a cat tree there if you have kitties; some are designed especially for corners ( the trees, not the cats).

No vase of sticks, and no hooks. Who wants to see a bunch of coats hung up there?

Why not leave it empty?

Thanks e everyone. I like the shelves or leaving it empty. Just making sure it wasn't a mistake to leave empty. I'll work on shelves or leave empty. ;)

I liked the plant Grover showed. They are very trendy right now.

Not a mistake to leave it empty!

I would say 2 long mirrors or something like this in between

There's an update to sticks in a vase

Some ideas, quite like the topiary pot plants

There's nothing wrong with leaving it bare, but it's also a possible location for a sculpture item placed on a pedestal.

Geez, no topiaries.

One of the rare luxuries in life is empty space. Room to move, room to breathe. We do not need to fill every corner of every room. Negative space lets the eye rest between focal points, too many points reads as cluttered and confusing. So enjoy the luxury, and leave that corner empty.