No. They can't play chess on a grandmaster level without a harness programmed to make it possible. Simply training an LLM on chess games isn't enough.

It's moronic to suggest a "formal" definition of a commonly understood word is somehow necessary to say whether that word applies in a given situation.

LLMs cannot write poetry via understanding what makes good poetry. They generate tokens. They do not know whether those tokens are poetry or a recipe for cat food. Because they cannot know anything.