Getting the size of a child

I'm trying to build a FlowStack (a container view that will layout its children on rows, depending on their size and how they fit the parent). The problem I'm facing is that SwiftUI calculates the size of the children (even if implicit) only at a later time, so I can't get it like we used to `view.bounds.width` right after I create the `View`

I tried using `anchorPreferences`, these sort of work, however they do not allow me to rearrage the children, but create new ones in foreground or background, so it's a bit useless for my purpose.

How can we get the implicit child size from the parent?

Getting the size of a child
 
 
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