Iirc when my kids were in y2 they had a topic called fairy tales. The teacher would recap a story that they all knew like 3 Little Pigs then the kids would write it in their own words. As they knew the order that the story happened, they could focus on stuff like making interesting sentences. (By interesting I mean more colourful words, using connectives to make sentences longer- whatever the current writing targets are)
On a different week, the writing task might be creating their own different ending. As the story is familiar, most kids would only have to worry about the end being different.
I also remember my child telling me about a lesson where it was explained that stories were like a mountain. The beginning of the story would be at the bottom of the mountain, the middle of the story was at the top of the mountain and the end of the story is the bottom of the other side of the mountain. His goal was to write a paragraph for each at the time )might have been end of y2)
In my kids school, they did Big Write. There would be a topic announced by the teacher one lesson, a lesson where they planned their writing and a lesson where they wrote their piece. They did Big Write until y6
Can he retell a story verbally? It might be worth practicing that skill if he finds that hard.
Come to think about it, I remember my kids doing a cookery lesson in y2 and they had to write the recipe later. I suspect this is to help with developing a proper beginning/middle/end mentality