I don’t see that option? There is no indication anywhere in Discourse preferences on how to set a profile image, Gravatar or otherwise. I stumbled across a reference to Gravatar by accident ( Welcome to McNeel Forums ) and am horrified by the idea that I must create a WordPress account to create one? I can see that this is a very old complaint - no action yet?
https://discourse.mcneel.com/search?q=gravatar
I’m far more concerned about the spam potential of creating a Gravatar account than I am about the insignificant programming burden of supporting profile/avatar images specific to this forum.