Is it possible to adjust the size/frame of a ImageView when focused using imgView.adjustsImageWhenAncestorFocused = true ?
Been scouring the webs but can't find anything that would set the zoom size of the effect, seems to just be some default value.
It seems you can't do that. And I think Apple doesn't allow doing so for a reason.
There are very detailed human interface guidelines for tvOS. They recommend spacing and item size for a grid layout with different number of columns, so that the viewing experience is optimal:
The following grid layouts provide an optimal viewing experience. Be sure to use appropriate spacing between unfocused rows and columns to prevent overlap when an item is brought into focus.
I guess the "default" frame for the focused UIImageView takes these recommended item sizes into account. And Apple doesn't allow to change it, because it might cause issues, like other grid items being overlapped.
So you can't modify the frame of focused UIImageView, but you can access it indirectly - by using focusedFrameGuide property.