The client_id parameter is not required to access the well-known. Including it just means that the data you get back (namely about things like the eligible grant types and token_endpoint_auth_method) will be specific to the client in question, but all the endpoints returned will be the same (for the same issuer), regardless of client.
Thanks for the respons.
and about the yourOktaDomain: is this client specific as well? there is no way we can just use one url for all our client(implementations)?
The endpoint itself is only Authorization Server specific, so if all of your applications use the same authorization server, then yes, they would use the same well-known endpoint