I have a template in A1 but there isn't an option to set the paper size to A1 - how can you print for A1 in ArcMap??
Click your Properties button to the right of your printer name.
You dialog will look different than mine unless you have the same printer but there should be an option to select a custom size and name it. You can name it A1
However, I am surprised you do not have A1 as an option. Each of our plotters has A1 as a paper size. If you don't have the plotter selected that might be your issue. You may need to set it up as a PDF. That also will show A1 as a default size
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