The NTAG I2C plus has the unprotected memory starting from page 04h of sector 0, and NDEF messages are stored there.
Referring to 8.3.11 of the data sheet, AUTH0 specifies the starting page to be protected, ACCESS[NFC_PROT] enables read&write password protection from NFC interface, PWD and PACK are for password configuration, but before changing any of above , you have to do a password authentication as below:
Then you may select sector 0 and read the contents starting from E3h.
Here FFh is the default value for AUTH0.
Now you may change the AUTH0,ACCESS[NFC_PROT] , PWD and PACK as you wish, for example, something like below: read the data from E3h to E6h and change the corresponding bytes in one write.
The video shows how to read the NDEF message under password protection.