basically, there is a certain range of idrive firmware for 2017+ cars which can accept a patch which can turn the 2/3 carplay into full screen carplay. you'll need to contact them with your current firmware version and the last 7 digits of your vin. they will let you know if your current version firmware can accept the patch for full screen. if not, then they will confirm if you can update your firmware to an acceptable range which can be patched.
1. firmware version (example NBTevo_J16383I)
2. last 7 digits of your vin
enquiries@brdiagnostics.co.uk
you can send a photo of you current iDrive version or write it down (in your car open the Navigation Map, then hit the options button next to the iDrive controller and go to Navigation Settings > Position and Version > Version Information)
if you idrive firmware can be patched, there will be a paypal requirement for the patch
