The chip in question is RHD2164, you can see the DDR part on page 10 and 11

Looking at the ESP32-S3 datasheet section 3.5.2 Serial Peripheral Interface (SPI), in the SPI2 General­purpose SPI (GP­SPI) mode part it's mentioned that SPI2 can do DDR at 40Mhz while in half duplex mode. In the project i have a SPI slave chip that does DDR on the MISO line, as in MISO line needs t...