Yes, you can configure the maximum PST file size created by Migrator for Notes to Exchange (MNE) before rolling over to a new PST file. Here is the parameter than can be added/adjusted in the Global Default Settings:
[General]
MaxLargePstSize=<########>
By default MNE sets this value to 20480.
However, you can change this value by adding it to the Global Default Settings, like the example below:
[General]
MaxLargePstSize=40960
