Ideally, yes. While many people will find it possible to work from home from a laptop alone, laptop screens have two major disadvantages. One is there small size, which is great for portability but less great for viewing your work, especially if you work across several different programs or windows at once.
The second problem is their position. If you put a laptop on your desk the screen will almost certainly be below your natural sightline meaning that you have to look down at it. Over days, months and years spending so much time in that position can be bad for your posture. Using a laptop shelf isn't always an ideal solution either since it often means your keyboard will be too high to type on comfortably.
Using one of the best monitors for working from home helps resolve this by allowing you to keep your laptop on your desk but position an external monitor level with your eyes. For other options to improve your posture when working from home, see our guides to the best office chairs for back pain and the best standing desks.