iPhone Encryption. AFU and BFU

Hey all, I’m really interested in how encryption works and I was doing some research and found out that like desktop encryption, the data on an iOS device is only fully encrypted before the device is first unlocked after booting. (I realize that changes were made to the A12 silicon so that brute forcing methods always operated at BFU speed, and I should point out my device is an iPhone XS Max)

My question is this, assuming my device is powered on, and a criminal or other person that wants access to my device, and shouldn’t have it, has taken it. The device is powered on, but the screen is locked, and it is in AFU mode, since only some of the data is encrypted then, could they then extract all that data?