Every big enough system has a few parts that would fit OOP, and a few parts that would fit FP. If your language supports those, then great, use those for them.

Every big enough system has a few parts that would fit OOP, and a few parts that would fit FP. If your language supports those, then great, use those for them. The overwhelming majority of problems do not fit OO, and using OOP on them makes a mess. Similarly, FP.