I need to know if in the new midi/expressions command center can we change an amp channels with exp1/2 like in another devices like in helix
If you want the QC to send amp channel change commands, then it already can via MIDI, as long as only one CC/PC is required. The update will allow you to send more than one command per QC footswitch press though.
If you want it to send amp channel changes via jack switching, I don’t believe that is ever going to be possible.
If you want it to receive amp channel change commands (for blocks in the QC), then yes, it can already do this via Midi, expression, footswitch expression etc.