As we know, the Best Practice is not to include text in images. However, there sometimes exceptions (like legacy images) and it's good to know how to handle them.
As an example, this complex image from the department of Health and Human Services, their alt text clearly describes the text as well as the image's graphic elements:
Text reading “What are endocrine disruptors, and where do they come from?” A circular graph with text in the center that reads “Some Sources of Endocrine Disruptors.” Icons of seven disruptors appear around the outer rim of the circle. They are labeled “Bisphenol A (BPA), Dioxins, Flame Retardants, Phthalates, Pesticides, Phytoestrogens, and PFAs.” The HHS logo is at the bottom right of the graphic.