default or selected kernelversion does not have config value CONFIG_NCPFS_SMALLDOS.
Result is shown for kernelversion 6.7-rc3

Lowercase DOS filenames


Linux Kernel Configuration
└─>File systems
└─>Network File Systems
└─>Lowercase DOS filenames
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
If you say Y here, every filename on a NetWare server volume using
the OS2/LONG namespace and created under DOS or on a volume using
DOS namespace will be converted to lowercase characters.
Saying N here will give you these filenames in uppercase.

This is only a cosmetic option since the OS2/LONG namespace is case
insensitive. The only major reason for this option is backward
compatibility when moving from DOS to OS2/LONG namespace support.
Long filenames (created by Win95) will not be affected.

This option does not solve the problem that filenames appear
differently under Linux and under Windows, since Windows does an
additional conversions on the client side. You can achieve similar
effects by saying Y to "Allow using of Native Language Support"