Accent wall color can only be a different color than other wall colors, or have a completely different design in terms of colors and materials.
The surface of the accent wall can be paint, wallpaper, brick, marble etc. As the name implies, the accent wall is usually meant to break the pattern created by other walls, especially when the walls are painted in a flat tone.
However, the room can be coated wallpaper and has a wall of accent that is untouched and unadorned, because it will suit its purpose. The point is just for aesthetics alone or to accentuate or frame some decorative elements, such as painting.
Here's an app catalog:
accent wall ideas for living room
accent wall designs bedroom
accent wall ideas for kitchen
accent wall ideas with paint
accent wall ideas for dining room