@Pramod Kalvala
As of now there is no built in processor in NiFi that could extract Json attribute dynamically because if we add significant number of attributes dynamically to the flow file, As attributes are hold in memory this will cause performance issues.
We need to add all the json keys/attributes and matching json path as value in EvaluateJsonPath processor and change the destination property to flowfile-attribute to keep them as a flow file attributes.
Please refer to This link for more details regarding dynamic attribute extract processor.