The idea of a new top-end 1TB SKU in the next-gen iPhone series has been raised and then shot down again in leaks emanating from market analysts trying to assess the new devices' specs and success ahead of their launch. However, the latest such tip asserts that this new option will indeed be announced by Apple during its upcoming product event.
https://www.notebookcheck.net/1TB-2021-iPhones-are-back-on-the-table-as-is-LiDAR-for-all-variants-new-leak.552104.0.html