How to change the width of the widget
In Also Bought, it is possible to change the width of the widget on Visual preferences, just go to the Visual styles section:
Click on the whole widget image to access the Widget preferences:
You can type the desired width or leave it empty for unlimited width:
In the screenshot below you can see an example of the widget with the width left blank to fit the entire container width:
If we reduce the size to 800 pixels, the widget will now look like this:
And if we reduce the size to 550 pixels, the widget will now look like this:
Every time you change the widget width, you will probably also need to adjust the product box width and/or margin between products, so that the product images best fit the widget.
You will probably also need to adjust the app name size as well so it fits better.