Hello 香織 鈴木
Welcome to Microsoft Q&A Platform, thanks for posting your query here.
If you used Azure Portal in a sandbox environment provided by Microsoft Learn, you should not be charged for any services used during the learning process. The sandbox environment is designed to provide a safe and free environment for learning and testing Azure services.
However, it is always a good idea to check your Azure subscription to ensure that there are no unexpected charges. You can check on your subscription the details.
If you do see unexpected charges, you can cancel your subscription to avoid further charges. From subscriptions menu:
Hope this helps.