Should a manual tester learn automation? Should a automation engineer learn DevOps? Should a DevOps engineer learn development? The questions go on and the answer is always the same "Depends on context and your individual interest".
If you want to be a Automation engineer you learn automation, if your team doesn't have a dedicated DevOps team who are not aware of how to integrate a test automation to pipeline then you have to learn the basic to guide them in the right direction.
Similarly if you want to work in a team that has been using RPA tools you should else don't need to, if you want to be a technical architect then it's good to know a different genre of tools and have a strong ability to critically evaluate the benefits and cons of each tool and choose the right tool depending on your team needs.
So simple answer is you don't have to learn RPA but just a basic idea on what it is and what is the cons and pros.
The greatest asset of an engineer is to learn and critically evaluate the knowledge; not to swallow something as it is.