about Boss GT 10

[Likui]

is it possible to make a patch whereby the expression pedal is originally set to Pedal bend and I set it such a way that it lowers down the pitch by 1 semitone and then after that I step on CTL 1 and it becomes a volume pedal and when it becomes a volume pedal the pitch lowered by 1 semitone still remain. Can this be done? if yes how

thanks