I used GPT 3 to help write my halloween one shot a few years ago.

The outcome was pretty good. As a language model it had quite a good understanding of tone and context. In fact it ended up adding (without my notice, I was quite tired) a whole layer of subtext, after the game my players were like "Ok now explain the goo!" and it turns out, that in 2 handouts, and 3 scene descriptions GPT had added linked, veiled descriptions of some space goop that I hadnt planned for.