[keycloak-user] Policy by Client (microservices)

Hello Team, I'm new in Keycloak authorization, I've read all the documentation already. I would like to know if there is a kind of *Policy that can match Client name* (maybe thru Rule based JavaScript). I'm creating an API Gateway and I want to validate who is trying to reach who other (restrict by ClientId). Thanks a lot. Regards. -- Ignacio Ocampo Millán