I'm using this handbrake... https://www.hsxsimracing.com/
It goes from 0% do 100% just fine in the options screen, but inside the car, the handbrake full range is limited to the first 10% of the physical handbrake controller.
Everything past 10% (ish) is just full handbrake.
I don't think I need to record this, because it's been reported so many times since 2019 that codemasters should know about it.
Also, this is on PC, no XBOX.