And what exactly is the attack vector if you just store that unencrypted? I mean compared to storing that data encrypted.
I the original question was if there is special hardware on the ESP32 to support safe storage the answer is no (at least to my knowledge).
But you can program the eFuses to disable external access. But this might disable software upgrades and the likes too.
The ESP32 supports flash encryption in hardware so you can encrypt your data but as I wrote earlier, you have to think about what type of attack you want to defend against. An attacker with physical access can read the encryption key too given the device is not nailed by eFuses.