Stepping outside your normal comfort zone to try new things as a writer is one of the most vitally important things you can do to improve your craft.
Do you normally write short? Write a novel. (And vice versa)
Have you only written stories? Try telling one in a different media: make a video trailer, write a screenplay, write a script for virtual reality, design a game.
Do you write only science fiction and fantasy? Write a romance. Or a mystery.
Have you always written as yourself (i.e. under your own name)? Write under a penname. Secretly. BE THAT NEW PERSON. See what it does to your writing.
These things may seem like a waste of time. Or painful. Or something you simply don’t want to do.
But here’s the thing: you will steadily improve your craft by writing lots and lots of words; you will take significant leaps by earnestly studying the craft itself and applying it to your work; but you will take warp-speed jumps by doing something radically different with your craft (and then bringing those lessons learned back to your regularly scheduled writing show).