Their datasheets only mention the PIN definitions and electrical characteristics of the microcontrollers. Try to get the information from the reference manual[0]. Also there are these books[1][2] by Neil Kolban.
The ESP32 datasheet is really woefully inadequate for this part; it mostly describes the chip, but I guess what I'm really looking for is things like "A description of the ISA itself", i.e. the "LX6 datasheet", so to speak. So I want something like the the actual instruction encoding, instruction listing, etc for the LX6 series and what it supports precisely.