In documentation, there is a description of length parameter in padding(_:_:) method.
The amount to inset this view on each edge. If
nil,the amount is the system default amount.
What is default "system default amount" value? If I understand correctly, user can change this amount, e.g. by changing display zoom in settings.
This was already answered by the user emreoktem in this post.
As far as I understood from Apple's documentation, there's no standard value and it's calculated based on some criteria by Apple. So, it may be different for different devices, accessibility settings of user, if user is using the app in side-by-side mode on iPad, etc...
Here is the documentation:
The set of edges along which to pad this view; if nil the specified or system-calculated amount is applied to all edges.
