When you work with both 8.5” x 11” and A4 paper size documents, Word may automatically scale printouts to your default paper size. If you want to print to a different paper size and you're not getting the results you want, you can disable automatic scaling.
Turn off the setting to scale paper for A4 or 8.5" x 11" sizes
Tap File > Options to open the Word Options dialog box and then tap Advanced.
On the Advanced tab, scroll to the Print heading.
Under that heading, clear the checkbox labeled Scale content for A4 or 8.5 x 11” paper sizes and then click OK.
The change will apply to all future printouts.