As someone posted on a different thread a few days ago:
“The FA Community states:
Where are temporary dismissals used?
Step 5 and below in the Men’s football pyramid and Tier 3 and below in the Women’s football pyramid. It is also used in all cup competitions in leagues at grassroots levels and all County cup competitions where there are no teams whose clubs play in the National League or above.
They are also used in the following FA Competitions:
FA Vase
FA Sunday Cup
FA County Youth Cup
FA Inter-League Cup”
That said - sin bin use should be stated within the Competition Rules.