Generate API Oauth2 or api Key to Validate input Payload and Response SAP APIM via SAP BTP suite.

How to generate oauth2 api from sap apim
1. validate request from api, through error in api itself if not valid.( json input)
2. call to sap btp integration suite api.
3. based on its response , generate payload for success and failure.
Reach me same type of requirements.