A family of Microsoft word processing software products for creating web, email, and print documents.
In Word, choose to print the document.
In the Print Preview window, the bottom setting is labelled '1 page per sheet', select that, then at the bottom of the resulting list, click 'Scale to paper size' and you can select the paper size you want to scale the printed document to.
For example if your document in Word is A4 and you want to scale that to an A5 paper size, you can do that from in there.