Listing role assignments of a subscription via REST API

Hello, I want to list the role assignments for a subscription using the REST API. I'm following the documentation [here](https://docs.microsoft.com/en-us/azure/role-based-access-control/role-assignments-list-rest). However, it seems like I'm not able to achieve the wanted behaviour. Is to possible to do a API call which is doing the equivalent to

the following done via the Azure portal UI.. Selecting a subscription >> Selecting Access Control(IAM). I want the response from the API call to return the role assignments either in "All scopes" or in the "This resource scope" as shown in the screenshot bellow.

The issue points to the Azure role-assignments REST documentation and the portal's subscription IAM view; start by comparing the documented scope parameters with the portal request. Done means confirming the supported API call or identifying the REST API specification change needed to expose the requested assignment scope.

Written by the indexing model from the issue text.