There are several free graphics software programs on the Internet. creativebloq.com has an article called The Best Free Graphic Design Software.
Serif DrawPlus is Windows software program that is an alternative to the graphics package Adobe Illustrator. It is free (Starter Edition) but they have an upgrade to a paid edition. Here is an instructional YouTube video on working with text in DrawPlus.
You might also consider an Internet web-based program called Lunapic. If you are looking for free graphics, try Pixabay.
If you want to draw diagrams, you might consider Google’s Drawings under the Home and Office section. Another option for drawing your own diagrams is www.draw.io. It is a website that allows you to draw your own diagrams and save them in different formats.
Here is an article on 5 free network diagramming tools.