At this point in its lifespan we consider Django REST framework to be essentially feature-complete. We may accept pull requests that track the continued development of Django versions, but would prefer not to accept new features or code formatting changes.
Apart from minor documentation changes, the GitHub discussions page should generally be your starting point. Please only raise an issue or pull request if you've been recommended to do so after discussion.
The Contributing guide in the documentation gives some more information on our process and code of conduct.