I made a video. Sorry for my english, I learnt it in grocery and mall, just to survive a month in NY!
See the video:
I'll try to explain with text and pictures with a similar example:
Are Fusion Assemblies respecting parametric Paradigm?
My answer is: partially, in a way that make it useless in many cases. It’s because Fusion has not parametric “instances” ore “derivates”, call them as you want
A sample
[MISSING IMAGE]
This is my parametric component. The hole is positioned and sized with a parameter.

This is my assembly: on the left side you see 2 parts, linked to original component, while on the right side you have 3 parts, unlinked from original component, so you can change diameter, individually for each.
Obviously the 2 on the left have diameter fixed and defined in the original file (they are linked).
Now, I open my original component and change it
[MISSING IMAGE]
I added a sketch and an extrusion, so I changed a little detail that was not planned. Say I didn’t know it was necessary, and when my technicians revised the final project, with hundreds of these parts inserted, they say we need it.
This is the effect when updating the assembly

No way to make unlinked derivates to show extrusion!
So, if I change a part I cannot update it in assemblies (if I unlinked it, obviously). I can make many similar parts with copy / paste new or unlinking, but they are not a “parametric” part, they are copies, and even a little little change needed in my "parent" part will break my project. You cannot simply update your parent part and then update your project: you’d have to remove and reinsert all the “instances” of your part, with the same individual parameters, breaking joints and projections, and so on…. You’d better redraw all from scratch or reinsert again all instances with the same individual parameters after reimporting…. but it’s not only boring: if you miss something or you make something different from previous project, it will not fit with yet produced pieces, and your boss will fire you!