CONFIG_METAG_BUILTIN_DTB is not available for thedefaultarchitecture x86.
Result is shown for architecture metag
default or selected kernelversion does not have config value CONFIG_METAG_BUILTIN_DTB.
Result is shown for kernelversion 6.7-rc3

Embed DTB in kernel image

configname: CONFIG_METAG_BUILTIN_DTB

Linux Kernel Configuration
└─>Processor type and features
└─>Boot options
└─>Embed DTB in kernel image
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Embeds a device tree binary in the kernel image.