The State Flow Designer allows configuring transitions between the states. In particular, it is used in the practices state models (for example, Incidents State Model, Changes State Models).
You may need to configure transitions for the specified practice (for example, Incidents). For this, you have to create a state model first, and then you can configure transitions.
The model ITSM Incident for the Incident table exists. And among others, there is the transition:
In this screenshot, the Completed state can change to the Rejected by User. Closed, In Progress and Assigned states. Also, if the state will not change for the three days 8 hours (on an 8-5 weekdays calendar; it's equivalent ten working days 8 hours each), then it will happen automatically.
We can see transitions defined by this model for the Completed state on the incident form.