How to implement depending on the architecture

Hello friends.

Basically this is the question, how would you do the implementation of some automatic tests for api (in my case I want to use playwright and typescript) knowing that the architecture is about 20 microservices.

I do not have much experience in the field, but I think it would be best within each microservice to make the implementation of the tests for that particular microservice, since the tests, none makes a connection between them, they are all tests aimed at each particular microservice.

I heard from some that having a microservice, they make a separate repository, and do everything there, but it seems to me that it would be something huge and I'm not really convinced.

What do you think?