I've coded in a lot of different programming languages over the past forty years or so, some of them for fun, some of them as part of my job. I've also coded C

I've coded in a lot of different programming languages over the past forty years or so, some of them for fun, some of them as part of my job. I've also coded COBOL at a few places, both on PC and on mainframes years back. But I can honestly say that I have never done anything in COBOL for the fun of it. However this is not to dissuade anybody from ever doing this. COBOL and a few other old languages are still used in areas like banking today. So you might cross it at some point in time, even at the most modern workplace. But as others have written in the comments, there is more to it than the language itself. You should really have a mainframe emulator (like Hercules) and other parts of the environment like CICS, TSO, ISPF and JCL if you really want to know how it feels like to code in COBOL. I don't know if it's even possible to get all of this up and running for free, but that could be a challenge in itself.