Another alternative to ui.expander can be a simple stepper. If you feel like a multi-step form could make more sense than a single cramped form, make sure the user is well aware of what the current step is about. The data collected should be grouped contextually, with a group name used as a step label.
q.page['form'] = ui.form_card( box='1 1 4 2', items=[ ui.stepper(name='stepper', items=[ ui.step(label='Order info', done=True), ui.step(label='Personal info', icon='ContactCard'), ui.step(label='Payment info', icon='Money'), ]) ])
Don't forget that your multi-step form should have easy navigation back and forth between steps and should accommodate data validation before proceeding to the next step.
That means the
Next button should be disabled until all the required fields are filled correctly.
name attribute indicates how to reference this component in the query arguments:
Check the full API at ui.stepper.