X66 is a network interface. multiple network connections with different functions can go through X66 interface. IF your KRC has PRofiNet or Ethernet/IPO option, then ProfiNet and Ethernet/IP messages will also pass through X66.
those messages can contain standard or safety signals or both.
note that those are just data signals that end up in PLC memory.
to physically connect real wires you need appropriate IO (standard or safety or both) on the PLC side and you need to write program for the PLC to communicate with KRC and transfer those signals.