This entry was published at least two years ago (originally posted on January 16, 2020). Since that time the information may have become outdated or my beliefs may have changed (in general, assume a more open and liberal current viewpoint). A fuller disclaimer is available.
The Tokyo 2020 Official Art Posters are fascinating, with a wide range of styles and imagery. I’m particularly fond of this one for the Paralympic games, which has a very retro-SF feel to it.
A bonus: This 73-page, 15MB .pdf showcasing summer Olympic posters from 1896 to 2016.