Club3D makes some dongles that will convert from DP 1.4 with DSC to HDMI 2.1, actually. The only ones I've used personally are physically USB-C (DP alt mode) on the DP end, though. But they make some that are mDP and have DSC support as well, and they might also have one for full-sized DP, although I bet it requires external power.
Edit: The article claims that a good Club3D adapter for this has disappeared. Yeah, there is an old Club3D adapter (CAC-1085) for this and it's not around anymore (and it does require external power!). But it's been superseded by a newer one (CAC-1088) which is still available on Amazon, at least in the US. (And the new one is bus-powered.)
You can make up some difference with DSC, but I think that requires the display to support it: dongles won't decode it.