CONFIG_INTEL_TDX_HOST is not available for thedefaultarchitecture x86.
Result is shown for architecture 64BIT

Intel Trust Domain Extensions (TDX) host support


Linux Kernel Configuration
└─>Processor type and features
└─>Intel Trust Domain Extensions (TDX) host support
In linux kernel since version 4.14.330 (release Date: 2023-11-20)  
Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
host and certain physical attacks. This option enables necessary TDX
support in the host kernel to run confidential VMs.

If unsure, say N.