Browse 1800+ free icons from Font Awesome & Google Material Design directly in Google Docs. You can choose any color you want and the icons are imported in your document with a transparent background.
A very simple way to choose the perfect icons to illustrate your doc.

For now, 2 icon set are available via this add-on, for a total of more than 1800 icons:
- 900+ icons from Font Awesome - https://fontawesome.com/icons
- 900+ icons from Google Material Design - https://material.io/icons/

Once you selected an icon and added it in your doc, right-click and select "Format options" to drop a shadow, add a reflexion and much more.

Insert Icons also exists for Google Slides & Google Sheets!
https://chrome.google.com/webstore/detail/insert-icons/ebobdijloifekdgihhibghageadfgbml
https://chrome.google.com/webstore/detail/insert-icons-for-sheets/fnchdighbkgihmmjcheadelfcmhocmpi