We need pictures. :-)

I could've sworn I posted pictures but this is the first time I'm using the forum so pardon me!

Really nice room.

You may have space for a narrow end table against the interior wall but you'll likely need to choose a floor lamp for the other end of the sofa. Would likely choose a brass or chrome similar to your coffee table and overhead light. This one might work on both ends.

https://www.potterybarn.com/products/delaney-marble-floor-lamp/?pkey=cfloor-lamps&isx=0.0.204

You already have the beginnings of color with your rug and chair and art so you don't need all that much more. You might see if you can find a couple of throw pillows that are either a solid color and/or contain the colors you already have in your art -- wouldn't crowd the sofa with pillows though..

Afterthought:

Don't limit the pillows you consider to the traditional square cushions. Consider other shapes as well. You may even find a "stuffed animal pillow" that appeals to you.

Very nice room.

Have you considered a small ottoman --adding textures to your room in lieu of or in addition to new colors might be worth considering:

https://www.article.com/product/11590/hira-metal-gray-30-ottoman

Here are some possibilities for throw pillows. Do you lean toward modern?

African Bantu Pillow, Rust and Gray Authentic Lumbar, 12"x20", With Insert · More Info

Cowhide Brown Animal Fur Decorative Throw Pillow, 21"x21" · More Info

Lucy Pillow, Maze Pillow · More Info

Trenza Pillow 18x18x4, Polyester Fill · More Info

Some more you might like:

Neil Lumbar Throw Pillow, 18"x12" · More Info

Nitro by Surya Poly Fill Pillow, Burnt Orange, 22' x 22' · More Info

Surya Dots 18" x 18" Medium Square Pillow Cover HH081-1818 · More Info

Ellen DeGeneres Crafted by Loloi Rust/Beige Jute Pillow, 13"x21", No Fill · More Info

It doesn't appear that you have room for end tables. Keep curtains close to the wall color. The total width of the curtains should be 1.5-2 times the width of your windows.

I really like the pillows that Diana suggests. Love your artwork too. Your space has great style!

Thanks Ida!

@suezbell how would I use the ottoman? As an alternative to the end table or just as a foot rest?

@dianabythelocks Yes my tastes run more modern. The main floor is a mish mash at the moment but style will align soon enough.

I like the rectangular cushions but didn't think I could use cushions on leather furniture! Who knew!

The chair without arms might use an ottoman. That, however, might involve moving/turning your rug and focus on using the rug and coffee table for sofa or at least changing the angle of your chair.

Thanks for your contributions everyone. Much appreciated.

Catch all, As far as pillows on leather, I haven't heard that before. Maybe the pros here can answer that. I would suggest ones that aren't slippery like satin.

Another option would be a throw; sample:

Candler Throw, Paprika · More Info

All of these were here on Houzz. You can shop by style, color, shape, etc.

I don't think pillows are right for your modern leather sofa. Is your rug new? It should be quite a bit larger to ground your furniture. As far as lamps, a brass arc floor lamp would work well.

@Maureen Wow! Thank you so much! The coffee table is new but can be used elsewhere or sold as I do see your point about practicality.

I was actually leaning towards cream curtains as I think the room needs lighting up. Rug was repurposed from another room but can be changed to a bigger one.

I better get to work so I can take advantage of the weekend sales!

Thank you all!

I'm not disputing the pros, but I did find modern leather sofas with pillows. Maureen, above, suggested more subtle colors, and this picture exemplifies that. It's up to you!

Modern Bonded Leather Sectional Sofa with Chaise · More Info

Check rugsusa.com for an area rug. They have free shipping with so many options. It looks like you could use a 9x11 or 10x12.