If it's drive by wire the brake pedal cuts the revs. If it's cable then the revs will stay put.
What I've done in the past when bedding in brakes was to drive at a constant speed, and gently apply the brakes to warm them up slightly. Can't do that anymore, as soon as the brake pedal gets pushed the engine dives towards idle.
I suppose left foot braking is 'probably' not too good on the road....