Whether you missed a side quest of there are some fiends you haven’t taken care of yet, you always have the option to travel between regions in Final Fantasy VII Rebirth. However, you need to unlock that option first and this guide will explain how.
How to Travel Back to Regions in Final Fantasy 7 Rebirth
Use the Chocobo Carriage at any ranch to travel between regions in Final Fantasy 7 Rebirth. Before Chapter 4, there is no need for the carriage, so you won’t find it in the Grasslands until later. Once you reach the Junon Region, you need to unlock the Chocobo Carriage at Gabe’s Ranch. You can find his ranch northwest of the Mythril Mines directly after completing Chapter 3 in the main story. He will help you get a new mount for the area and is the first step to a carriage.