Not sure I understand your question, but the ESP32-S3[1] is the "CPU" here.
I'm not sure why you are not sure - S3 was using Cadence's Xtensa 32-bit LX7 dual-core microprocessor, but the article on S31 only mentions "dual core" without too much detail.
Formal grammar / technical documentation style guides consistently define:
[ ... ] = optional
{ ... } = repetition
| = alternatives