Since SQL Server 2016, Microsoft has separated SSMS installation from SQL Server Engine installation, and the SQL Server setup page now includes an option to install SSMS.
I previously wrote a blog post about using PowerShell and the registry editor to modify the default installation path for SQL Server Management Studio here.
Since then, I’ve tried a few alternative approaches, and now I’m back with a new method for installing SQL Server Management Studio via the command line to a user-specified location.
Microsoft has separated installation of SSMS from SQL Server Engine Installation since SQL Server 2016 and if you see the SQL server setup page it has an option to Install SSMS
Saurabh Srivastava's SQL Server Blog 