Different rules apply if you are using an image as part of a class assignment versus creating something you plan to publish.
From Visually.
Google Searches:
Images on a general Google search are likely copyright protected, but there is a way to narrow down the results to usable pictures and graphics.
"Open access" availability does not mean that the images in these collections are in the public domain--rather, it refers to their accessibility for research and educational purposes. For copyright and use restrictions, locate and read the image use policy for each collection.
All guides are available under the CC-BY-NC-SA license.