That’s all well and good. But, where exactly can you find these images without getting in any sort of copyright trouble? Your best best is to search for royalty-free images online. But ...

An image such as a drawing or photograph is typically protected by copyright. If you want to use an image that you did not create, you generally must obtain specific permission from the copyright ...

As stated on their website, all images are released under Creative Commons CCO into the public domain and can be used royalty-free, including for commercial purposes. Attribution is not required.