I have written to various site's legal compliance people when I have found my images in someone else's portfolio. Most sites take care of the problem although some - Shutterstock, I'm looking at you - are unbelievably slow. In a couple of Shutterstock cases, twitter-shaming got them unstuck after a long wait with no action.
DMCA takedown notices also work, but they're a pain to do and so that's only if there are no other options - FAA has a Shutterstock collection and had one of my images in it. I wrote to FAA in October 2020 to ask them to take it down as my SS account was closed 6 months earlier (SS has 90 days to remove from partner sites). FAA wrote back and told me to submit a DMCA takedown notice, and it was eventually removed.