Question - are the window coverings currently on the windows reducing your light? Maybe changing that element will be the driver of other changes. Possibly Roman blinds fixed above so when they are up the full window is open.

The placement of the sectional cuts off the view to the bay window. This makes the room appear smaller. It would be helpful to see the other walls of the room, and know dimensions. Is it possible to put the sectional with one side against the stairs, the other where the sideboard is? Also, the many different small shelves give a cluttered look, and don’t balance the visual weight of the sectional. Replace them with one or two large pieces of art, or group some of the frames and hang them directly on the wall so they read as one unit. Repeat the blue color of the entrance with some pillows on the sectional, so the rooms connect.

I agree the seactional does not work where it is but if you want a brighter space you need lighter furniture and a lot more lighting and gray probably not the best choice for wall color with a brown sofa. Those little shelves do not work there add some art that teeny lamp does nothing IMO you need a sofa not a sectional, remove the window covering and add some ceiling lights in LEDs 4000K and also lamps same bulbs

The sofa, rug and console are keepers. The rest are do-overs. Can you move the sectional?

Constine and Patricia have the right ideas, but if there is any way you can change out that sectional for a sofa it would be a great help. In the meantime, remove all but basic furniture, rug that you must keep and start moving things around. That includes shelving, etc.

Use a lighter paint color, remove small shelving, put your record collection in a cabinet, add a floor lamp in far right corner, separate the sectional if possible (huge dark furniture makes the room seem small and dark).

Thanks for all the input! I think the furniture is pretty much stuck where it is because of the placement of the fireplace and tv (in front of the stairwell). The only other option is to place sectional on the wall beneath the record collection, but then we’d need chairs on the opposite side to make tv watching practical.

The Roman shades can be drawn up for better lighting during the day, but we also need them for privacy as we have a sidewalk right outside those windows.

I would consider cellular blinds that can be raised from the bottom so you have privacy and light.

Or temparary window film to frost the windows! If the windows are an upper and lower pane, just do the lower ones, leaving the uppers clear .

Show pictures of the other walls and give dimensions of the room. You’d be surprised at some of the creative options you might get.

If we can't see stairwell, can't see TV, can't see fireplace, it limits suggestions. Stand with your back to the window and take a photo to add so all four walls can be seen. As requested, give dimensions. Several have pointed out that gray walls + massive brown sofa + little sticking out bookshelves shrink the room down.

It just looks like you can do better with your layout. Please post additional pictures.

You don't have room for a lot more furniture, so additional lighting could be attached to the wall. Look for wall-mounted plug in sconces. I would put 2 pair of them in your room and it will really improve the feel of the room. It's more attractive than overhead lighting and opens up the space when the walls are well-lit. They are often reasonably priced because they are not that large. For the flattering even light, choose a white fabric shade or frosted glass. No Edison bulbs. These or these

I love your retro record player..

Decor-wise, you have a lot of small square things all about the same size. The albums as wall decor, the pillows, the picture frames over the sofa. I'd take down the picture frames and add some non-rectangular things to those shelves. Small pictures look good grouped in a hallway where you can see them up close, For the shelves try a big green hanging plant such as pothos. Round sculptures or bowls are good. Thrift stores often have large round or curved vases. They can be spray painted any colour, even glass ones. Maybe bring in more repetition of the blue colour from the hallway.

For pillows, see if you can get pillow covers for your existing pillows, in a dark colour so they don't contrast with the sofa. Maybe a dark blue pattern. Then you can still have them but they won't stand out and you room will feel less busy and more coordinated.

the sectional is too big for the space. and it's very dark. if you want a lighter space, you'll have to try 'lighter' furniture. Not just in color, but in size. it just makes the room cluttered and cramped. any way to move that elsewhere, sell it or buy a new one?

to give you some ideas, here are some other similar sized rooms w/bay window

this first one is cool because it has a sofa that fits perfectly in the bay space

Sorry but I don't understand why the TV can't be moved to the wall on the right. Even if you have no cable connection in that location, there are solutions to this.

I agree with taking a photo from the window . You have a small dark living room because of your oversized dark sofa and dark furniture . You have to lighten up and how about moving the tv ?
Actually it could be a beautiful room ...if only you can try switching the sofa around ...or even break it up on both sides ...more pictures would give you more options .