It is already quite creative. One of the first ways that GPT was used in was to create text game adventures with the GPT generating rooms, environments and storylines.I like that! Will it learn to become creative over time? As that would surely change everything.
It also depends on what you train it on. If you use a large number of fantasy novels as its data and then tell it to write original stories, it will. This is an example of what GPT 2.5 could creatively do with the right training: