Use cool colors: purple, blue, green, blue.
Prefer pastel colors to bright shades.
Smooth plain or finely patterned wallpaper will visually enlarge the room.
In a small room, what frames the walls, namely baseboards and other wooden parts, can be made one tone darker than the walls.
This will highlight the architectural “skeleton” of the room, and the walls will seem to be pushed into the background.
In addition, thanks to this effect, the room will seem larger.
Dark and thick curtains visually make the room smaller. Light and light - increase.
If you are not particularly shy, you can choose completely weightless options that will only frame the window, make the room more airy and let in a lot of light.
Plain fabrics that can be smooth or textured are optimal.
The texture should not be too shiny, nor heavy or fleecy.
In small but tall rooms, you can use materials with a dim and narrow horizontal stripe, which will visually expand the space.