UDP.read(packetBuffer, MaxSize);

Hello friends,
I would like to know that what is the maximum size of the buffer we can initialize for UDP packet in UDP.read(packetBuffer, MaxSize); I have tested it for around 100 bytes and it worked well. I want to know the upper bound of this array.

Thank you

I want to know the upper bound of this array.

For which Arduino? The EthernetUDP class derives from UDP, which derives from Stream, which means that there is no limit imposed by the library. The limit is imposed by the size of a network packet, which you are free to investigate, and by the particular Arduino you are using.