It is generally possible to upgrade the parking assist system on a BMW vehicle by adding hardware and software components. However, whether or not a specific upgrade is possible will depend on the specific make and model of your vehicle and its existing features and capabilities.
To determine whether it is possible to upgrade from parking assist to parking assist plus on your BMW, I recommend consulting with a BMW technician or a dealership. They will be able to assess the specific features and capabilities of your vehicle and advise you on what upgrades may be possible. It is also possible that the necessary hardware and software components may need to be ordered and installed by a BMW dealer or a certified mechanic.
In general, upgrading the parking assist system on a BMW typically involves adding sensors or cameras to the vehicle and installing the necessary software to enable the additional features. The specific components and steps needed to complete the upgrade will depend on the specific vehicle and the desired features.