The arrangement tab is not an option in the display settings? Why?

The arrange pane appears only AFTER your external display has been recognized.

Otherwise, there is nothing to arrange and the pane stays hidden.

The arrange pane is not used for Target Display Mode, which has some very strong restrictions that go with it.

You cannot use an iMac as an external display for a MacBook Pro or vice versa. It was possible with older (pre-2015) iMacs and older versions of MacOS, but no longer.