Normal DisplayPort 1.4 can do 6K120 if you use DSC @ 9bpp instead of the usual 12bpp.
I think Thunderbolt 5 can do UHBR20 (77.37 Gbps) which requires 29bpp to do 6K120. That's almost 0 compression.
Thunderbolt 5 can do 120 Gbps, which can handle a couple UHBR13.5 connections (52.22 Gbps each) or a couple UHBR20 connections if they are limited to <60 Gbps each.
The display could be like the existing XDR and use a connection for each half of the display but that was only necessary to support GPUs that don't support DSC. The connections were HBR3 (25.92 Gbps) but limited to ≈19 Gbps each to fit in Thunderbolt 3. The existing XDR used HBR2 with DSC @12bpp for GPUs that support DSC (bandwidth less than that of uncompressed 4K60).