Tipster @patrickschur_ reports that an AIB Radeon RX 6800 XT part boosts to 2.5 GHz and beyond when running 3DMark 11. The sample was listed as an engineering sample, indicating that retail clocks could go even higher.
https://www.notebookcheck.net/Big-Navi-ASUS-ROG-STRIX-Radeon-RX-6800XT-allegedly-boosts-to-a-remarkable-2-5-GHz-in-3DMark-11.499281.0.html