How can I style this built in shelf?

I can’t tell how rough or smooth the wood is in this picture.

Buy mirrors at dollar store & double stick tape them to the back wall of this unit, after you paint the exposed wood whatever color your drapes or upholstery or rug is.

If you want the shelf edges to look upgraded, nail some molding to the front edges.

If you want deeper shelves, then glue and nail 2x2’s across the front, with the edges beveled or chamfered. Paint to match.

You could mod podge a pretty wall paper or fabric to the back and repaint the shelves in a different color besides to make it more fun.

How about hanging plates or other artwork with command adhesive strips.

Paint it white and use to display something like framed pictures , antique bottles, or a collection of your favorite of family items.

I would paint it and cover the back with self stick wallpaper.

You could removed the shelves to create a niche then use it to display a picture or some 3D art

I would paint It white and display your favorite family photos and/or canvas pieces.

I have the same built in . It had shelves. We removed the shelves and attached a flat screen tv .