cut and dried
US /ˌkʌt ən ˈdraɪd/
UK /ˌkʌt ən ˈdraɪd/

1.
already decided and not able to be changed
:
•
The outcome of the election is not as cut and dried as some people think.
•
There's no cut and dried solution to this complex problem.
already decided and not able to be changed