PowerColor has done AMD's work for it. While AMD is yet to reveal the Radeon RX 6600 series, PowerColor's website reflects that both the RX 6600 and RX 6600 XT are on the horizon. AMD teased that it would announce the RX 6600 series by June 2021 at the latest.
https://www.notebookcheck.net/PolorColor-confirms-that-AMD-is-on-the-verge-of-announcing-the-Radeon-RX-6600-and-RX-6600-XT.549086.0.html