Hi Sunil,
See https://community.st.com/s/question/0D53W00000HLDkKSAX/improve-rf-field-st25r95 for similar question.
Basically, Increasing power by putting 5V has benefit in the transmit path but have also impact on receive path because their is no modification on chip sensitivity and thus Tag answer may be not seen correctly.
Therefore, ST recommends to use 3.3V configuration with ST25R95.
If it is needed to increase the reading distance for your application, I would recommend to use either the ST25R3911B or the ST25R3916B reader device.
Rgds
BT
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