Hi @Nishra Nasar Greetings! Welcome to Microsoft Q&A forum. Thank you for posting this question here.
You can create a new Service principal role and assign Reader/Contributor permissions for that role to your API Management instance. You can add this role assignment through Access Control -> Add role assignment tab of your APIM instance.
Once you assign the access, you can generate a Bearer token for this role by calling the https://login.microsoftonline.com/{{tenantId}}/oauth2/token
endpoint from postman. Please refer the article Azure REST API - Create a bearer token which outlines all the steps needed to get and test the token.
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