If you're still struggling to add pix of the space, you must wait until the faded look becomes full color, then submit.

Dark walls will make the room seem smaller. Dark ceiling will make the ceiling look lower. Lighter colors will always make a space seem larger. Blues and other cool colors make a space seem larger while warm colors ( reds, browns, oranges ) make a space seem smaller. The walls can be lighter than the ceiling but the ceiling should not be substantially darker - for instance a light blue ceiling with off-white walls should work fine.

IMO in the right place dark walls seem to recede it depends on many issues and without pictures there is no way for us to know your space, BTW wall color is usually decided after your bedding is chosen. Post you pic in a comment waith until it is no longer grayed then submit if you have another add to the same comment and flollow the same steps. I have found 2 pics is the max per comment/

following

I am, also, of the opinion that a small room can be painted a darker color. What makes a light small room look smaller are the shadows in the corners. A dark color reflects less light blurring the edges of the room., By absorbing the light, "the walls of the room are less clearly marked and can give an illusion of more space."

I would consider removing the crown molding, as it is one more thing defining the size of the room.

Is there a light in the ceiling? Often a semi-flush up light gives the feeling of height.

I wouldn't remove the crown molding. One way to make a small room look bigger is to paint all the trim and walls the same color. This avoids the choppy look when there's a lot of contrast between the walls and trim.

Check out this dilemma: https://www.houzz.com/discussions/5385319/red-velvet-chair-dark-grey-headboard-chestnut-floors-what-rug