These two tweets, which are by the teenager in question.
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The first is just them sharing a photo, but the second is an image they uploaded which, as far as I can investigate, is not an image taken from somewhere else, meaning it's an image they captured.
It isn't concrete and may be difficult to confirm if they really are dead as there's no identifying info on this individual. However, the TransW account is still undergoing heavy criticism from the trans community for being seen as responsible for this individual's apparent suicide, and TransW has a fairly large Twitter presence and the resulting trainwreck is causing a huge stir across the platform.