ntfs3 64bit cluster size: does it auto-convert the fs?

[David Niklas]

Hello,
Regarding the option NTFS3_64BIT_CLUSTER, will the Linux kernel
auto-convert FS-es using 32bit clusters, or does this need to be
explicitly asked for when creating the FS with mkfs?

If enabled, will the Linux kernel not be able to access 32bit NTFS FS-es?

Thanks!