Gnome Shell 48 on Debian 13 does not provide a built-in (GUI) way to define a keyboard shortcut that lets me switch to virtual desktop 5. The "Navigation" keyboard shortcut settings only show "Switch to desktop 1" up to "Switch to desktop 4", but no more.
I found the solution in the blog post Gnome 3 and ‘switch to workspace 5 and above’ shortcut:
$ gsettings list-recursively org.gnome.desktop.wm.keybindings | grep switch-to-workspace org.gnome.desktop.wm.keybindings switch-to-workspace-1 ['<Super>1'] org.gnome.desktop.wm.keybindings switch-to-workspace-10 @as [] org.gnome.desktop.wm.keybindings switch-to-workspace-11 @as [] org.gnome.desktop.wm.keybindings switch-to-workspace-12 @as [] org.gnome.desktop.wm.keybindings switch-to-workspace-2 ['<Super>2'] org.gnome.desktop.wm.keybindings switch-to-workspace-3 ['<Super>3'] org.gnome.desktop.wm.keybindings switch-to-workspace-4 ['<Super>4'] org.gnome.desktop.wm.keybindings switch-to-workspace-5 @as [] org.gnome.desktop.wm.keybindings switch-to-workspace-6 @as [] org.gnome.desktop.wm.keybindings switch-to-workspace-7 @as [] org.gnome.desktop.wm.keybindings switch-to-workspace-8 @as [] org.gnome.desktop.wm.keybindings switch-to-workspace-9 @as [] org.gnome.desktop.wm.keybindings switch-to-workspace-down ['<Control><Alt>Down'] org.gnome.desktop.wm.keybindings switch-to-workspace-last ['<Super>End'] org.gnome.desktop.wm.keybindings switch-to-workspace-left ['<Super>Page_Up', '<Super><Alt>Left', '<Control><Alt>Left'] org.gnome.desktop.wm.keybindings switch-to-workspace-right ['<Super>Page_Down', '<Super><Alt>Right', '<Control><Alt>Right'] org.gnome.desktop.wm.keybindings switch-to-workspace-up ['<Control><Alt>Up'] $ gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-5 '["<Super>5"]' $ gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-6 '["<Super>6"]'