Select a chart and open the Chart view size tab in the command bar. Tick the “Fixed size” option. This enables you to edit the “Width” and “Height” fields by typing in your custom chart dimensions. Please note that these dimensions are in pixels.
You also have the option to add your custom dimensions to the “Favorite sizes´ drop down list by clicking “Add.” You can share the defined sizes with your colleagues by saving them in your company account.