Almost nothing in this chapter is a one-way door — but the setup wizard is not the door for changing it. The wizard exists only to get a new company off the ground; a signed-in company administrator who opens it is taken straight to their own company in Company setup, with a note saying so. That is deliberate: the wizard works in profile templates, and a template must never be able to flood a running business's tuned configuration back to defaults mid-operations.
Changes to a running business are made directly in Company setup: modules and workflow depth on the Workflow & modules page, and the feature switches on the company record's Features tab — the same switches the wizard's Features step presents at birth, there opening on your company's current choices, and nothing changes until you change it and save.
Two cautions belong here. First, the guards still apply: depth cannot move from Standard to Simple over open orders (§0.5), and a module cannot be switched off beneath a dependent (§0.4). Second, reversible does not mean free of consequences: turning a tracking switch on starts asking new questions on every form from that day, and your team should hear about it from you before they hear about it from a form. Change configuration the way you would change a shop layout — deliberately, announced, and not in the middle of the month-end.