To determine the comfort level of a sofa, it's essential to test it out in person. Visit furniture showrooms or stores and spend some time sitting on different sofas. Pay attention to the support provided by the cushions and the depth of the seat. Consider factors such as the firmness of the cushions, the angle of the backrest, and the overall feel when seated or lying down. Opt for a sofa that offers a comfortable and supportive experience based on your personal preferences.