i'd suggest a table/chairs designed for small spaces; maybe 4 chairs & a small storage bench to keep under the table until you need additional seating. If you have space, I'd move the sofa to the wall under the art, that will brighten up the space since it seems to be blocking part of your window. Get rid of the coffee table & red chair. I'd also ditch end tables/lamp & replace with a floor lamp & an end table that's more functional - something with a drawer/shelves.

Remove small wall decor pieces as they just add to feeling of busyness/ clutter. As suggested, remove heavy drapes, red chair, table cloth, etc. Pull the chairs closer to the couch so they can access needed end tables and eliminate coffee table. Start with advice given before making purchases. A less busy room will help you visualize what needs to be replaced. Take time to make your space the best it can be!

You've gotten good advice. IMO, you have the right furniture arrangement now with the exception of the red chair. If that were removed, I think the space would work and then it just needs tweaking to make it all cohere. Of course, if you want to buy all new smaller furniture, that would be even better, but not necessary, I don't think.

I will return to this room after my morning appointment to give you a few ideas.

I like those pictures, but it is hard to tell if you can walk in there comfortably. It looks good there. also, if you need the sideboard why don't you put it in the living room, in lieu of the red chair? it will make both the living room and the dining room appear less cluttered.

I believe no rug (or a lighter color rug) will also help make the space look more spacious

will the sidebar work under the window in the living room?

Following.....

This arrangement makes the space feel even more crowded. IMO, couch goes back in front of the window with two chairs flanking and minus the red chair.

i think if the window in the dining room is clear it may work... give it a try. rug is pretty, but also dark....

In the future, I need to reload the page to see what you've already done before I post. ;-)

Do you need the red chair? The room would be so much more open without it.

following

Red chair in a nook, or wide entry....?

Quick thought... can you find another spot for the red chair? Moving it against a wall will make a big difference by opening up the center of the room!

Variation of quatrefoil hmm in wool expensive, but to me, repeating wood and warm neutrals there.... is chair a grey-green [nice with gold] -

Kaleen Helena Rug, Beige, 8'x10' · More Info

https://www.houzz.com/products/kaleen-hand-tufted-helena-beige-wool-rug-8x10-prvw-vr~96244789

Even this neutral might brighten the darker neutrals in room - good reviews in wool and jute:

Falling Leaves Geometric Print Pillow, Teal, 16"x16" · More Info

Anji Mountain 8' x 10' Zatar Wool and Jute Rectangular Rug AMB0308-0810 · More Info

[https://www.houzz.com/products/zatar-wool-and-jute-area-rug-8x10-prvw-vr~39077932[(https://www.houzz.com/products/zatar-wool-and-jute-area-rug-8x10-prvw-vr~39077932)

Posting something cutesy:

Faux Suede Blue Throw Pillows Cover 16"x16" Throw Pillows Cover - Full Bloom · More Info

https://www.houzz.com/products/full-bloom-blue-faux-suede-16x16-throw-pillows-cover-prvw-vr~14606227

One too many sofas in the room. An L shaped couch would work wonders in your space.

With your furnishings, etc... a bit too 1970's?

Felt Tree Pillow, Off White, Green, and Brown, 16"x16", Spring and Summer Colo · More Info

Felt Tree Pillow, Dark Gray, Red, Orange, 16"x16", Fall Colors · More Info

https://www.houzz.com/products/felt-tree-pillow-dark-gray-red-orange-16x16-fall-colors-prvw-vr~53909218

Cute rooms!!

Normally, I'm not a fan of naked windows, but I think yours looks better without the drapes. It give of a "loft" vibe...

I think that streamlining is important here...If a new table is in the cards, make sure you get one that's narrower than what you have. Also, the different chairs does, as you can see, contribute to the crowded look...those along with the stair rail makes a forest of spindles that's visually confusing. I would get cleaner chairs. How about 2 chairs that are upholstered, and then they can be dragged into the living space when you have more people? Then the red chair can go into a bedroom?

Angi, here is the rug:

Uptown Rug from Next Generation by Orian | PlushRugs.com · More Info

https://plushrugs.com/orian-rugs/next-generation/uptown/#off-white

And the lamp:

Possini Euro Cherry Finish Wood Surveyor Tripod Floor Lamp - #W1650 | Lamps Plus · More Info

https://www.lampsplus.com/products/possini-euro-cherry-finish-wood-surveyor-tripod-floor-lamp__w1650.html

Lower your art in the dining room.

If you want to take it to the next level, find a big piece of art you love for that spot:

The next level: an even bigger piece of art.

Yes, it really does get hung this low. Art goes at eye level and eye level is lower when you're sitting down.

This light is 26.4" wide and $125 at World Market:

Antique Brass and Glass Globe 5 Light Alessa Chandelier | World Market · More Info

It is amazing how much visual space a tablecloth eats up. Your changes so far are good!

@Laurie Tillet, I found it at art.com. It's by Ryan Fowler and lots of places carry it. He also has others including Doodle Beer. https://www.art.com/gallery/id--a268777/ryan-fowler-posters.htm

Fabric for warmth?

Disco Wall Tapestry · More Info

https://www.houzz.com/products/disco-wall-tapestry-34x52-prvw-vr~98804948

If you keep red chair [and not sagey] - would your rug be too dark, adding charcoal items and gleam for 'lift'....

"Black Horse II" Painting Print on Wrapped Canvas · More Info

https://www.houzz.com/products/black-horse-ii-painting-print-on-wrapped-canvas-prvw-vr~61150368

Idk if this would look messy with your current pair on wall? something like...

Lucas Field, Gallery Wrapped Canvas, 30"x40" · More Info

https://www.houzz.com/products/lucas-field-gallery-wrapped-canvas-30x40-prvw-vr~70906880

red item, for red chair:

"Red Elephant" Print on Canvas, 40"x40" · More Info

https://www.houzz.com/products/red-elephant-print-on-canvas-40x40-prvw-vr~40026757

Lighter curtains in dining room. I like side bar at window. with two narrow tall lamps. Love what Grove done. I was going to say remove LR drape too.