At a much smaller and less costly scale than Starship, Stoke Space (Kent, WA) has a plan and has published CGI videos of a proposed fully reusable second stage.

At a much smaller and less costly scale than Starship, Stoke Space (Kent, WA) has a plan and has published CGI videos of a proposed fully reusable second stage. Along with something very similar to a Falcon 9 resuable first stage. Whether they are actually able to do it remains to be seen.