Yes, that works if you are riding a pretty simple profile - continuous speed on a flat road.
If you are doing a lot of uphill and downhill, it will change all the time.
Just imagine this: you ride the last 15 km flat with tailwind over 25km/h (or 20Mph) with your battery below 10%. It will display a huge range since you are not using any juice.
Now you hit a hill and put in a full battery. It will display an enormous range (let's say 128km on Turbo or even more) as it still sees you are not using any juice but still going fast. But the 128km range will be a true less than 20km as you are going up that steep hill for the next 10km with average 12% grade (1200m elevation gain, pretty much the limit on one battery in Turbo depending on the total weigth).
Just check the
Bosch range calculator for mor information.