Open an existing page in VE
Blank the content.
Open "Page settings", check "Redirect this page to", set another article and save.
The resulting redirect still holds the categories and other non visible settings the original page had, like TOC DISAMBIG INDEX {{DEFAULTSORT:}}
While the rest of the settings do not harm, categories keep displaying the empty redirect in category pages (probably the same categories with the target page).

See Also:
T128187: Prompt the user to delete all other page content when creating a redirect