I have a 2021 RAM Limited Longhorn that came with the black rails and soft tonneau cover.
I don't know what a 2021 Limited Longhorn comes with the 10th anniversary edition but a 2022 Limited with the 10th edition does not come with a soft tri-fold.
The night or red editions force the soft tri-fold, with the 10th you would need to manually add it.
It does show black rails at part of the 10th edition, noted as
"4 Adjustable Cargo Tie-Down Hooks by Mopar®"
So at least on a 2022 the BUG or any other package (10th, and night ed) that includes "4 Adjustable Cargo Tie-Down Hooks by Mopar®" triggers the black rails. I don't see any silver rails on any of the rambox configs. In fact I think if I recall they listed silver rails as "not compatible" with my vin, which obviously was incorrect.
On the 2023s you get the cargo divider with BUG or the Elite Package.
Night edittion doesn't give you the cargo divider but does give you the soft cover still.
BUG and elite package also appear to include black rails without a cover.
So looks like no matter what config of 2023 Limited with Rambox you get, you are stuck needing to buy silver rails out of pocket.