Throttle-by-wire, yes: any modern car has this. Steer-by-wire or brake-by-wire, no. If the power dies, you can still steer to the side of the road and apply the brakes.
On the good old BMWs with hydraulic steering, you could get Active Steering, i.e. variable steering. They basically introduced a planetary gear set: https://www.youtube.com/watch?v=unL8HpMeVTA
If today you buy a BMW with Active Steering it means you get rear-wheel steering (on top of the standard front-wheel steering, but don't tell the execs, you don't want to need a subscription for front-wheel steering).
On BMWs since the F* (with the electric assist steering) variability was achieved by a variable-ratio steering rack.
