How to simulate JTAG burning the slave chip ESP32 through the SPI module software of the main control chip?

[yangh_]

Hi,
The main control chip I am using is XMC4500F144, and the slave chip is ESP32_WROOM32U. The slave chip is only connected to the main chip with four pins, IO15, IO14, IO13, and IO12, for SPI communication. Except for 3.3V and ground, all other pins are not wired and are in a floating state. May I ask if the ESP32 is a slave and the EN pin is not wired and in a floating state? Can the chip function properly? How will I verify if the code has been burned inside the ESP32 chip? If the program has not been burned in ESP32, how can the ESP32 chip be burned through the four pins IO15~IO12? Can you provide some solutions or sample code for similar situations?
The ESP32 wiring diagram is shown in Attachment 1.
Thanks.