I am using mac os sql developer version 184.108.40.206.5
I did not see the beautify tool icon like the link below describes
Is there a plug in I need to install?
You are confusing plsql developer, a third party "tool", with SQL Developer, the free Oracle client tool.
SQL Developer has a quite advanced offering for formatting code for Oracle SQL and PL/SQL. Well worth using/getting to know
Tools -> Preferences... -> Code Editer -> Format + Advanced Format + Custom Format...