The Ten Rings

This episode of Marvel Studios Legends is about Ben Kingsley's version of Mandarin from Iron Man 3 in preparation for Shang-Chi and the Legends where the real Mandarin is revealed. It is a reminder to what there was already to the Mandarin in the MCU. This series tends to be about recapping the adventures of particular characters before new projects post-Infinity Saga as promotion for the film/show and a recap for those who need it. Shang-Chi is a film in the MCU that doesn't have much from what was released previously. It could be good to know what happened with Ben Kingsley's character beforehand but still. Travor Slattery/Mandarin has only appeared in Iron Man 3 and the Marvel One Shot All Hail The King. Watching those would help give a more in depth perspective of the character, though if you want to skip straight to Shang-Chi and the Legend of the Ten Rings, watch this. Watching the stuff with the characters in these episodes would give a little more detailed look at the characters though these episodes would be good if you don't have the time to watch hours of content (though the Mandarin would be less than others).