I dont believe HDMI 2.1 cables are official yet.
Kordz was preparing a series of Bravo cables rated for 48Gbps but they were delayed until the official testing specs are out - eg DPL testing like they do for their 4K range.
I think even then, it is not rated for long runs yet.
https://www.kordz.com/8k-cable-guide
This company claims they have one that will do 56Gbps but as I said i dont think there are any official testing specs as yet.
https://www.fibbrtech.com/details.php?id=1