This the correct way and why SPOILERS FOR DARK PHOENIX
X-Men First Class
X-Men Origins Wolverine (never happened after DOFP)
X-Men (never happened after DOFP)
X2 X-Men United (never happened after DOFP)
X-Men The Last Stand (never happened after DOFP)
The Wolverine (never happened after DOFP)
X-Men Days of Future Past (only Wolverine remembers events in 3-...
What we saw in Apocalypse wasn't the Phoenix Force.
It's not a retcon, because it's not said, in Apocalypse or Dark Phoenix, that this power we saw at the end of Apocalypse was the Phoenix Force.
Rather, it's a transition/climax scene of sorts which serves two purposes:
establish how powerful Jean is currently
plant the seeds for the upcoming Dark Phoenix ...
This was what could be called a retcon
Reframing past events to serve a current plot need. The ideal retcon clarifies a question alluded to without adding excessive new questions. In its most basic form, this is any plot point that was not intended from the beginning. The most preferred use is where it contradicts nothing, even though it was changed later ...
It's a sexual predation reference.
It's difficult to not get explicit, but, wiping his face and then saying that is suggestive of it bringing to mind him having ejaculate on his face, and it evoking memories of his scoutmaster.
"One-eyed Willy" would be a euphemism for a penis - which is often referred to as someone's "Willy," and the "one-eyed" reference ...
I found few explanations for the scene. Couldn't find any official statement so I'm putting both for you.
One is it's a reference to Josh Brolin's 1980s cult classic movie Goonies. Deadpool have few lines from the same movie which made Brolin famous.
Well, as Scoutmaster Kevin used to say... "There's a first time for
everything,son." Give me your best ...