How can I add a ps4 player as an xbox player without epic games id without having played together before but you know each other personally?

Anyone have any idea if so, write to me, by the way, it's about the game rocket league ^^

That would only work via the Epic-ID, because it can establish the connection between the platforms, because it is an independent network, because outside of it it would not be possible to establish a connection between Xbox Live and PSN.