Concept renders of the Xiaomi Mi Mix 4 have started springing up on Chinese media sites. While it's likely the Mi Mix 4 images are unofficial, they do give an idea of what the 2021 smartphone could look like. Unsurprisingly, an under-display camera is present at the front and the phone is not as curvy as recent Xiaomi models.
https://www.notebookcheck.net/Xiaomi-Mi-Mix-4-wows-in-concept-design-renders-thanks-to-under-display-camera-and-fresh-flat-screen.519800.0.html