>>212486744
Quill knobs have been found on velociraptor fossils thus it's conclusive that they also had feathers.
A species related to the T-Rex, the Yutyrannus Huali, also conclusively had feathers.
The jury is still out on the T-Rex itself, it's likely but not proven.

Nobody is saying "all dinosaurs have feathers", most didn't, this is your headcanon / strawman to cope with losing this argument.