The AWS documentation here says that the default block size is 4 KiB: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/volume_constraints.html#block_size
It says that 8 KiB, 16 KiB, 32 KiB, and 64 KiB are also supported... but I don't see anything in the documentation that says how to change it from the default, and I don't see any fields in the BlockDeviceMapping that allow you to configure this.
Is there some way to configure this?