Maybe yes. Maybe no.
If you ever write server/back-end software, it should be a requirement today that you know Docker.
If you create applications, it’s good to know Docker so you can create a standardized build environment. You never really want your application release builds to come off a developer system, and it’s even better if the standard build system can be defined in software.
If you want to run a specific version of a database on your development system, then Docker can do that pretty trivially as well.
If you have problems with version conflicts between various installed environments (Python 2 vs 3, various gcc[lib] versions, other tools installed globally, etc.) then Docker can be useful to set up the perfect environment to run a picky tool, and once it’s working you can share that environment with a coworker and know that it will just work.
Docker is a tool. You should learn it if it will help you do your job. The above examples are not exhaustive. Any time that it would be good to have a standardized environment on your development system, for testing or sharing or running specific software, Docker would be useful.
But if you never need it for the above reasons or otherwise, then no, you don’t need to learn it. It wouldn’t hurt to learn it just in case. But there’s no “should”. It’s really, really not hard to learn, though. At least if you understand the command line.