Is mewing cope for maxilla growth?

[Bootsmax]

I’m pretty sure I have a slightly recessed mandible and a pretty flat maxilla, I’ve seen a bunch of shit about how proper tongue posture (pressure on the upper palate) can help with forward and upward growth of the maxilla making your mandible follow making it less recessed.
Is that shit cope?

 

[Bootsmax]

Seen a lot of conflicting info on this