Yes, but in Apocalypse Jean herself states it is "not just the mind-reading or the telekinesis" but something else that she feels inside her growing.

Xavier screaming "Jean, let go!!!" Over and over was meant for Jean to use that unknown, growing power. It had the iconic Phoenix imagery. It was the Phoenix Force.

"All is revealed" as stated by Apocalypse, meant something. Perhaps he had knowledge of the PF.