What colors migh you like for an ottoman?

I was thinking dark brown leather or possibly neutrals with a pattern?

a few inspiration pics for ideas for yr space

If you don't mind my saying i would remove the hanging fixture or replace it with one more in keeping with the decor of the room.

I also prefer the rug design and size in the above pics or no rug at all.

Here's a whole page of ottomans, scan up and down. See if you can find one you like. footstool

Your room has great architecture and your furniture is nice. You just need to add some personality.

Is there a reason why you don't want curtains? Curtain panels can add a nice layer of color and texture and often make a room look more finished.

Your current rug is a bit small and seems too casual for your furniture. A subtle pattern would look great. I would suggest a larger rug and lamps for your side tables or some floor lamps.

I think a leather animal print would look great.

Are there any colors you are drawn to?

Here are a couple of rooms from which you might find inspiration.

I would choose 2 small tables that you can add anywhere

I love the idea of making your spaces work for your lifestyle. Your room is pretty small and the sofa is pretty large and your chair is large, so this is creating a bit of a problem. You might have been better doing a couple comfy chairs and an ottoman instead of the large sofa. Is the sofa staying? If so, you need a larger rug to "ground" your space. I would look for a combination ottoman/coffee table arrangement so you have the best of both worlds. Here is one to give you the "concept".

As to your windows, if you don't want to do drapery, simple woven roman shades would be very nice and provide privacy and some light. Another alternative is "solar shades". You can see through these nicely yet they bring some light through. Some protection for your floors and furniture.

I'd want to go with tufted to add a bit of texture to your very nice,but neutral room. Here are two from Joss & Main
https://www.jossandmain.com/Randy-Tufted-Ottoman-WRLO8663.html

'Randy' comes in natural or charcoal -

Or Colton, which comes only in this leather - HERE

I would do two end tables with matching lamps. You have a lovely space!

Are you able to get a new chandelier for the room? That would be very nice to see.

I like the size and shape of the ottoman that Flo posted above. It mimics the sofa shape without adding too much volume to your space.