Am I correct in understanding that you want to open Finder items in new windows instead of a new tab within an existing window? I had that problem. Very annoying.
This was my fix, which took me an unnecessarily long time to find:
- System Settings --> Desktop & Dock
- Scroll down to 'Windows" (below Dock, Desktop & Stage Manager, and Widgets — in that order).
- Set "Prefer tabs when opening documents" to "Never"

This solved it for me. Now when I doubleclick any item in the Finder, it opens in a new Finder window, as it logically should.
It appears that upgrading to Tahoe defaults the setting to "Always," which stupidly supersedes deselecting the Finder setting "Open folders in tabs instead of new windows," which is where that setting used to—and should—live exclusively.
Hey Apple! Why do we have the same setting in two different places, one of them buried, that disables the other? Seems to me that two different parts of the UI team need to get their stories straight as far as where this setting lives from now on.
Put it in Finder Settings, where it belongs exclusively.
Come on Apple, get your act together! We expect better…