Not a graphic designer? No problem, here is my list of places where you can search and find art which is public domain (free to use and abuse)
https://openclipart.org/
https://pixabay.com/
https://www.heritagetype.com/pages/free-vintage-illustrations
https://unsplash.com/
https://pexels.com/
https://thenounproject.com/
https://publicdomainreview.org/
https://picryl.com/ https://rawpixel.com/
https://freeimages.com/
https://www.flickr.com/photos/britishlibrary/