Difference in font sizes between Figma and Word

I am working with a client that generates customized Word Documents for their customers after filling out a survey. I created a mockup using the “Letter” frame and sent it over to the developers along with a text style guide. When the first report was compiled using the exact same font files and sizes I used in Figma, they take up way more space in the document in Word. Does anybody know where the issue might lie and how to go about converting the font sizes correctly?