What is causing the large fonts but normal printing
You tagged common. I understand this happens in all components Writer, Calc, Impress, Draw, Base and Math.
Without much description from your part, I assume you inadvertently zoomed in the screen view. Take a look at the bottom right in the status bar:
If it reads a figure like 200% (or more), either click on the number to select predefined zoom factors or use the slider (or the - button) to zoom out.
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