Whenever I provide feedback online (whether it be for Wattpad or any other platform), I almost always write the critique in a separate notes .doc. This way I can re-read it easily, give it a quick edit, then post it in chunks via pt1/2/3 in separate comments if the word count is larger than the provided submission box.
But I haven’t provided critiques on wattpad in years so I’m not sure if the system has changed (this whole new forum is immensely different to what it used to be!!). But it’s a useful habit to get into for all constructive criticism you give both on wattpad and outside. Sometimes I actually write notes in a notebook as I read/watch, write the critique in notes, THEN post it haha But that’s usually when I’m providing feedback on short films, docs, and scripts versus online stories.
Anyway, good luck.