Hi Namdev,
The RTC of S32K3 does not contain internal memory.
The RTC is present in always ON domain, hence available in RUN mode as well as in STANDBY mode. Both RTC and API timers can generate interrupts as well as wakeup from low power modes.
This chip supports seamless RTC operation across functional reset with the clock sources SIRC and SXOSC.

About S32K3 Emulated EEPROM, it is recommended to download S32K3xx_Memories_Training(AN744610) from Secure Files for a more detailed introduction.
NXP provides FEE driver with the Real Time Driver (RTD) package. You can also refer to the FEE example in S32K3 RTD.
Best Regards,
Robin