App restoration on Macbook Pro - will these apps be reinstalled whenever Big Sur launches? Before I delete iMovie and GarageBand on a shared MacBook Pro (I'm the admin), if I upgrade from MacOS Catalina 10.15.7 to Big Sur (whenever it launches), will they auto-restore on Big Sur being installed?
I know that if I want to reinstall I can do so via App Store, this question is more about the workings of Mac OS X.
If I remove GarageBand and iMovie from my MacBook Air, can I restore them later? was the question I saw which related to this.
My question is not about should I delete them, but whether these will be automatically re-installed anyway on upgrade from new OS (I'm not talking incremental, e.g. from 10.15.7 to 10.15.8, but to a completely new OS).
I would expect automatic installs of apps like Garage Band and iMovie not happening when Big Sur is released.
I would plan on these being easy reinstalls from the App Store.

The iLife and iWork apps are not part of the OS. Apple pre-installs them when you buy a new Mac which can lead people to assume they are part of the OS.  You need to download them again from the App Store if you wipe a machine and only install macOS.
This has been how it works for every release leading up to Big Sur so unless Apple makes a late change, count on signing in to the App Store to download any apps you don’t migrate from a previous backup.