You can create one or more special text files. These are “collection” files.
Then you select in any text file of your novel a piece of text, a word, a paragraph.
Then right click and “add to collection …”.
your paragraph ends up in a specific “collection” text file. The two are linked. Whether you edit in the original document or in the file, the changes are reflected in the other.
This way you get in 1 single text file: all dialogs, all description paragraphs, etc …