I know very little about later models but on my 2015 car the left hand stalk next to the steering wheel has a button on the end which when pressed alters certain things in the display eg ave mileage etc. Just see if you have caught thath and it's given you a blank screen. Also have a look at how to change MPH to KPH on the steering wheel controls. Otherwise it's back to the dealer. I hope that fixes it somehow but don't hold your breath.
The 2020 onwards XEs without the full digital display had this curious arrangement with analogue speedo and rev counter, but with about a third of the analogue dials blanked out by a digital display which reproduces what would have been seen on the analogue dials. At least with this arrangement, a blanked out digital display still leaves most of the analogue dials visible, so the car is still driveable and, I guess legal. A blanked out full digital display would make the car undriveable - which is now worrying me because that's what I have!
In many cases of blank screens on the XE, leaving the car switched off for 30 minutes will reset things.
That was only the infotainment screen and I have never heard of a digital speedo screen going blank before.
There was the "petrol station" fault that meant blank screens after filling up with petrol.
It was due to the car starting to shut down and then being woken up again mid-shutdown.
Kind of confused it's brain.
Later software is better and will sort itself out after a few seconds.
An alternative used on the Evoque forums is to disconnect the negative lead on the battery and wait 30 seconds.
It resets the car but you may have to reset things like the windows etc afterwards.
If all else fails then a trip to the dealer to have the software looked at.