From the Exporer view, right-click on any folder or file, then click Open Folder in New Window to launch a new workspace window with the selected folder as the root.
Note
When running Open Folder in New Window from...
a file, the parent folder will open in a new VSCode window
a file at the root of the current workspace, nothing will happen unless in a multi-folder workspace
the command palette, a dialogue will appear to select a folder (starting from the current workspace root)