CONFIG_BUILTIN_DTB is not available for thedefaultarchitecture x86.
Result is shown for architecture loongarch

Enable built-in dtb in kernel


Linux Kernel Configuration
└─>Kernel type and options
└─>Enable built-in dtb in kernel
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Some existing systems do not provide a canonical device tree to
the kernel at boot time. Let's provide a device tree table in the
kernel, keyed by the dts filename, containing the relevant DTBs.

Built-in DTBs are generic enough and can be used as references.