Transact-SQL script equivalent to the option: Apply Tracked Changes
There's an interesting discussion about this here:
https://www.sqlservercentral.com/Forums/Topic1480807-2799-1.aspx

and I reckon that you will find everything you need here:
https://docs.microsoft.com/en-us/sql/t-sql/statements/create-fulltext-index-transact-sql?view=sql-server-2017

Basically it seems to be something like: 

ALTER FULLTEXT INDEX ON [table_name] START UPDATE POPULATION