My child insists on the same route, seat, order, and so on.

Insisting on sameness is often a way of gaining security from being able to predict what's ahead, and it isn't bad in itself. First respect the child's sense of security, then prepare for change: when a plan may change, give notice in advance with pictures or words, show what the new flow will be, and get used to change starting from small ones. Forcing it apart increases anxiety, so adjust only the parts that interfere with daily life, little by little and in consultation with the child. Preparing with extra margin—on the assumption they're sensitive to sudden change—helps.