It seems to be a trace flag that pushes parallel processing.
Check this out: forcing-a-parallel-query-execution-plan
I basically understand that:
We can make a query to get an execution plan that uses parallel processing.
Then we can make the query use that execution plan and see the results.
"There’s always a Trace Flag", and as long as there is a trace flag there is hope.
I tried to attach the OPTION (RECOMPILE, QUERYTRACEON 8649) to the query but no effect in the query plan here.