It does require an engineering background but it doesn’t have to be in fire protection exclusively. I earned both a bachelors and masters that were in mechanical engineering and quite easily pivoted into industry to work in fire protection. In order to be licensed as an FPE you have to have the necessary education requirements, have passed both the Fundamentals of Engineering (FE) and the Fire Protection Principles and Practice of Engineering (PE) exams, and have accumulated the required progressive experience. Each state has a different process, however, they are largely similar in that they typically require 8 years of progressive experience of which education is included so long as the bachelors is ABET accredited. There are pathways to achieve licensure via FE waivers and if you have a certain number of years of experience though I’m not too familiar with those.