Does your co. version of the AFM include a derate chapter? IIRC a 10% derate chapter is typical - but I suspect Boeing does not include it in the basic price of the a/c. You have to pay extra for it.
But this begs the question - What is your SOP for contaminated runway? You cannot use flex (ATM) reduction, per FAA order.
Yes, we have charts for Derate 1 and Derate 2. The Derate values vary with aircraft and engine, to 20% max. However, we have switched to computed thrust values using Reduced Thrust for normal operations. All Reduced Thrust calculations use full TO thrust as baseline, and are limited to 25%.
Fixed derates are allowed on contaminated runways.