Whether or not someone (Age doesn’t mean anything unless you want it to 
) can learn software like UE4 is dependent on determination and persistence. My 11 year old sibling wanted to learn UE4 after seeing me working in it for a while, but after I gave them a small tutoring session, they changed their mind pretty quickly when they found out you can’t just magically throw games together.
UE4 is a big animal, but with time, the ins and outs can be learned.