You usually need a divan base to add storage space in the form of drawers. A divan is a bed base with a flat top, often upholstered in basic fabric. Of course, the larger the base, the larger the drawers, hence why they are usually quite chunky.
The size of the drawers can vary depending on the specific bed model, with dimensions typically around 53cm in depth and 22cm in height. The convenience of having storage directly under the bed makes storage beds with drawers a practical choice for many bedrooms.