The Page Outline on your map has a number of settings which can affect the area that is printed. These can be found by clicking on File and then Page Setup.
There are a number of paper sizes available to print your maps, these include standard ISO paper sizes – A4, A3, A2, A1 and A0. Whether you can print to any of the sizes listed will depend on your available printer(s). There is also a custom paper size option, which allows you to set specific non-standard dimensions in millimetres.
There are various scale options in the Page Settings but if the scale you require is not listed then you can type any figure in the box.
NOTE: both paper size and scale are linked and affect the map area that is printed. If the paper size remains the same then higher scales will print larger areas of the map. If the scale remains the same then larger paper sizes will print larger areas of the map.
e.g. An A3 map at 1:500 scale will show a larger area of the map than an A4 map of the same area at 1:500.
e.g. If your map is set to A3 with a scale of 1:500 and you want to show the exact same map area on A4 then you will need to increase the scale (in this example it would need to be roughly 1:750).