First order of business is to discover what your style is. In top search box, put in different styles, one at a time. Examples are: modern, contemporary, Scandinavian, transitional. Don't do or get anything until you have an overall plan. Do you have an inspirational piece of fabric, wall decor, or accessory from which you can pick a color. texture, or style?

None of this looks like precious or particularly comfortable furniture so why not donate it and start afresh?. It is hard to make suggestions for replacing it without seeing photos of the entire room and knowing what you absolutely must have in the room, how you are using the space. Is it also a bedroom?

True, none of it is particularly comfortable, the couch is too low and deep. It's a living room that faces a wooden dining table.

We are looking for a new couch that also goes around the corner so that it covers part of the radiator or all of it. The radiator is under the white pillow

I need to see the whole space and what kind of radiator is that

Assuming you do not use the radiator?
If not. I’d put curtains along the wall. Cover the window. The art is giving the illusion of more windows and I think it’s too serious for the space... what couch do you like? Show us some inspo? Can/would you go light? That egg shaped chair should go in a bedroom and then add some coffee tables, side tables, and fun accents. Vases. Pictures. Candles. Books.... 🥳

I would start with more photos, that show the light fixture and more of the room on the whole.