It’s definitely is prohibited to copy/paste code from licensed project into your own.
I mean nothing stops you, but on a trial it will be obvious if you’ve really did it and code analysis will find any “borrowing”.
You can draw inspiration and learn how to do certain stuff(Of course your patterns could resemble Epic patterns and there is nothing wrong with that, but pure copypasting is a big no-no)
Disclaimer: I’m not a lawyer and this is just my understanding of the law