default or selected kernelversion does not have config value CONFIG_IPDDP_ENCAP.
Result is shown for kernelversion 6.9.9

IP to Appletalk-IP Encapsulation support

configname: CONFIG_IPDDP_ENCAP

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>IP to Appletalk-IP Encapsulation support
In linux kernel since version 2.6.12  
If you say Y here, the AppleTalk-IP code will be able to encapsulate
IP packets inside AppleTalk frames; this is useful if your Linux box
is stuck on an AppleTalk network (which hopefully contains a
decapsulator somewhere). Please see
<file:Documentation/networking/ipddp.rst> for more information.