There's a nice little trick you can use in Word 2016 when you're re-sizing multiple objects.
1. Right click on an object and click on the Layout Options box, and then click 'See more'.
2. The Layout dialog box will open. Press the 'Size' tab.
3. Set the desired height and width of the object, and then click OK.
4. Now when you select the next shape (no matter if it's the same type of shape as the first one), and press F4, the next shape and any others you select in succession will be re-sized to the same dimensions. You can shift select multiple objects and apply the F4 command automatically to them all.