How to make REST API Call {GET & POST} from AEM author using OAuth

I have a situation where i need to make an AEM author post call from my OSGI Service, now we need some authentication to make this call , i tried with basic auth and it works absolutely fine. But i am looking for more secure option like by using bearer token and upon researching i found out we can use OAuth since JWT is deprecated. But after setting up OAuth i am getting 403 Forbidden from my api call response, earlier i used to get 401 unauthorized. Can someone suggest what should be the ideal setup for making AEM API calls using OAuth, it seems i have set it up incorrectly.