CONFIG_SOC_SP7021 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Sunplus SP7021 SoC support

configname: CONFIG_SOC_SP7021

Linux Kernel Configuration
└─>Sunplus SoCs
└─>Sunplus SP7021 SoC support
In linux kernel since version 4.14.326 (release Date: 2023-09-23)  
Support for Sunplus SP7021 SoC. It is based on ARM 4-core
Cortex-A7 with various peripherals (e.g.: I2C, SPI, SDIO,
Ethernet, etc.), FPGA interface, chip-to-chip bus.
It is designed for industrial control.