It isn't about the language but about the physics process you are controlling. To write software to fly a plane you need to understand how the plane works, same for power plants, saw mills, assembly lines, refineries, pipelines, etc.

Choose the process you want to control and then go work at a place that has that process or a consultant that supplies equipment or services to the owner/operator of the plant. Then you will learn how the process operates and how the software controlling it works, and how it could be improved.