@DocT hey there. I have been looking into this topic myself in the past:
The short answer is: it is not possible to increase the 2D clock via Radeon Software.
The longer answer and the "how to" actually achieve this, can be found here:
how to stop RX 5700 XT from downclocking?
The solution requires the freeware MorePowerTool (MPT) from IgorsLab.
This tool can change the registry entries (Soft Power Play Tables, SPPT) of the driver.
--- [ CPU: Ryzen 7 3800XT | GPU: ASRock RX 5700XT Challenger Pro 8GB | driver: 24.1.1 ]
--- [ MB: MSI B550-A Pro AGESA 1.2.0.7 | RAM: 2x 16GB 3600-CL16 | chipset: 6.01.25.342 ]