Programming always has a self-improving structure and you need to write and try programs to improve yourself.
Especially if you can read programs written by others. then it means that you can write a PLC program. Many languages are used in PLC programming. ladder and STL programming come first. LADDER is easy and mostly known because it visually appeals to everyone. With many lines of code that you cannot do in ladder or in LADDER plc programming, you can run it with much fewer commands with STL language.
How little staff usage and simplicity are important in plc programming as in all programming languages. It can be easily learned by only willing and devoted people. it is only necessary to work and produce something. As you produce, your programming language improves as you write something. And when you look back, you don’t like the programs you wrote before.
My advice, open to continuous improvement and practice by trying to understand plc programs written by others.