Yes, scale down (make it smaller) rather than scaling up. But at 1920x1080 you should be okay if the player has a larger monitor if you use high quality graphics.
Keep in mind a 2D game in Unity is not created on the canvas - only the interface is. The 2D, like 3D is created on the frame and you also have options to bring the camera closer or move it further away to fit the screen size based on the player's monitor size.