LibreOffice Writer 6.3.1.
Short answer: they should be independent.
However, I feel it doesn’t work well in all circumstances.
##Standard case
Your document page size is the same as your printer paper size. The layout setting allows you to print a reduced view of several pages on one sheet.
Works fine
##Other case
Your document page size is smaller than sheet size. Say you design an A6 document and you want to print 4 100%-sized A6 on an A4 sheet.
Though the File>Print dialog retrieves the sheet size from the driver, the page in Layout has the document chosen size (in the example above, A6 instead of A4). It is then impossible to achieve the goal.
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