Yes there is 4 pm check out based on availability for Diamonds.
Gold Passport gets this wrong often.
Even agents working for years at Gold Pass port screw this up.
I clarified this recently with a supervisor at Gold Passport
Both Reservations and Gold Passport said it does not exist as a benefit (sigh)
This all took place when a front desk agent at a property replied everyone has to be out of the hotel by 12 noon .No exceptions
And stated doesn't matter what you are we need to clean/make up the rooms so the staff can go home early.
An exception was made

Happy Travels and Late Check outs !
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AA & Starwood,Marriott Platinum
Hyatt, Hilton Diamond
Swissotel Club Gold
U/A 1k