With a real PN532 from DT (not a knockoff) I get a range of about 1cm from the board with a xNT.
it is possible to improve the antenna for greater reading distance, or that could be improved in the PN532 for a longer reading distance
Vulnerabilidades xNT Ntag216
The FlexNT has better range than the xNT because it’s bigger and has a bigger antenna as compared to the tiny glass tube. It’s purely physics. The smaller it is, the worse the range, the bigger it is, the better the range. That’s not the only variable though. Design of the reader antenna does play a role.
In practice, more than a 1-1.5 cm with an xNT has been a challenge.