This is the appropriate category, as your question has to do with adapting the model after loading it from the EW, not with something done on or by the EW itself.
The main reason not to use the scale tool is that it will scale everything in the selection proportionally. You can scale to an exact length if you type the units after the value. But, for example, if you increase the length of the bed by about 5% (say by changing from 76" to 80"), the headboard will also be 5% thicker. If you are just after a quick visual and the change is in that sort of range, you might not care. The increased thickness will be hardly visible. But if the change is more severe, the bed could look odd.
For more precise resizing, you can edit the component to move the geometry by the appropriate amount. If the bed model consists of nested sub-components, you will have to repeat this operation on each of them. Open the component for edit, select the geometry that needs to move (a left-to-right selection drag box is the easiest way), activate the move tool, and move the parts the required distance to reach the desired size.
One word of caution: if the model is actually a Dynamic Component, it may already have resizing functions built in or may have constraints that will prevent you from editing it easily.