Rest API authorization in microservice when you have 1000's of APIs

Question

We are developing back-office user application with lots of screens which interacting with lots of REST API's. In OAUTH, most of the tutorials are showing how to authorize an API by getting details from jwt and use it check whether to allow or decline (policy decision point) request. But most of the companies have 1000's API's to deal with and cant carry all the information, if we have 1 role for each API jwt can be very heavy to carry all the information needed for all the API's and also it can be very difficult to write code for each API in tools like OPA / API gatewaty services. How do we get Authorization process can be automated atleast to some level without writing code for each API or without carrying all the information in jwt and so jwt can be very light. I am looking for best practices that followed in big applications.