In the Tuesday stream, I was so glad Jess mentioned sources for graphics - such as Creative Commons. I’ll put in a shameless plug for this terrific resource; head over to https://creativecommons.org/ - and look at the top for the “Search for CC Images” link. From there, you’ll be redirected to a search tool that lets you filter your search for “Use commercially” and/or “Modify or Adapt”.
CC content can be licensed a number of ways; it’ll help you to do a fast review of the different kinds of CC licenses (About CC Licenses - Creative Commons) and what you can/can’t do with content licensed under each.
I’m not paid for the endorsement but work in academia (and we care a lot about proper attribution, how content is/is not used and taking advantage of inexpensive/free resources).
Hope you find what you need/want for your projects.