I have been asked to provide a set of drawings at 1:20 scale which will not fit onto my standard A3 Template. I thought I would just amend an A2 Template but under my list of Layout Templates I only see options for A4, A3 & A1.
I haven’t looked for A2 but you can create a custom sheet size. Just manually enter the dimensions in the Paper section of Document Setup.
Edit: Just opened LO and I see A2 is in the list of paper sizes.
If you are looking at the supplied templates, keep in mind they aren’t intended to represent every paper size and they really are just supposed to be examples and starting points for your own templates.