Heres how it works in Word 2019, 2016, and 2013:

Open your Word document.

On the next screen, underExport, selectCreate PDF/XPS Document.

To the right, selectCreate PDF/XPS.

Microsoft Word document with File highlighted

In the dialog, selectMinimum Size (publishing online)and choosePublishto generate the PDF.

In Word 2010:

Word 2010 works slightly differently.

Here’s what you should probably do:

Open your Word document.

Export highlighted in Microsoft Word

SelectFile>Save As.

In theFile namefield, put in your file name.

In theSave as typelist, selectPDF (*.pdf).

Export section of Word document with Create PDF/XPS Document highlighted

SelectMinimum Size (publishing online).

Preview comes with each installation of macOS (since the days of Mac OS X).

It will be located in your Applications folder.

Word Export section with Create PDF/XPS highlighted

From Finder, right-opt for PDF you want to open and chooseOpen With>Preview.

SelectFilein the Preview menu bar and chooseExportin the drop-down menu.

In the dialog box, in theQuartz Filtermenu, selectReduce File Size.

PDF dialog in Microsoft Word with Minimum size selected

bring up the iLovePDF app.

choose the location (equipment,Google Drive, orDropbox) from which you will retrieve the PDF document.

Give the app permission to access each location.

Mac showing Open with > Preview path

Navigate to the PDF file you want to compress, select it, and tapNext.

Choose the level of compression you want: Extreme, Recommended, or Low.

You will see a completion message.

Preview File menu with Export selected

To see the compressed file, tapGo to File.

Reduce File Size selected in Preview Quartz filter menu option

Save selected in the PDF dialogue box

iLovePDF app showing path to selecting a PDF to compress

Selecting and compressing a Google Drive PDF on an Android phone