2020.1 and later versions have an option to use the new non-modal Commit tool-window:

If you enable this option, the local changes will be in the Commit tool window.
Previous IDE versions have the following ways to view modified files:
-
Local changes tab (
View|Tool Windows|Version Control–Local Changes), default shortcut is Alt+9. -
Changed files Scope in the Project view
Previously the only way to view the changed files was via the Commit dialog:
Version Control | Commit Changes will show a dialog with locally changed files.