Some reference to AES is made in the technical reference manual, but I don't see a conclusive answer anywhere.
The Raspberry Pi 4 does not have cryptographic extensions, to be more precise it has, but to be enabled would require HW changes alongside paying a license to Broadcom/ARM.
Here's the link for a discussion on RPi's forum where a RPi foundation engineer explains the fuzz: https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=207888
jamesh's answer is straight forward:
That is licence for the HW, so you buy it then add the requisite HW to the die, so no, it cannot be added later without redeisgning the HW, which would cost about $1M Plus the licence....