In Spider-Man: Homecoming (2017), how did Tony Stark obtain Thor’s Magic belt (Megingjord)? It is mentioned by Happy Hogan when he's reading out the list of things loaded on to the plane they are using to move to new Avengers Facility.
The belt is officially known as Megingjörð , or more commonly referred to as the power belt.
In Spider-Man: Homecoming, Happy Hogan plays a significant part as the liaison between Tony and Peter. During one of their numerous conversations, he mentions one of the items that is being sent to the new Avengers HQ, which is referenced as Thor's Magic Belt.
It's a one-off mention meant for longtime comic fans, as the belt hasn't been extensively used in recent years. The belt is officially known as Megingjörð, or more commonly referred to as the power belt. It originally debuted in Journey Into Mystery #91 in April 1963 and multiplies Thor's already impressive strength.
While it isn't shown in the film, it's still a nice easter egg for fans
It's not shown/explained in the movie, it's just an easter egg for the fans.