Hello Gina,
Yes you can, you do this by utilizing the permissions and scopes blade for the AAD B2C Application Registration blade. More information on this can be found here :
https://learn.microsoft.com/en-us/azure/active-directory-b2c/active-directory-b2c-apps
https://learn.microsoft.com/en-us/azure/active-directory-b2c/add-web-application?tabs=applications
If you haven't configured any permissions or scopes in your AAD B2C Application then you won't be able to access anythign that's validating the access token for permissions. For more information on how the permissions/scopes work see here : https://learn.microsoft.com/en-us/azure/active-directory/develop/v2-permissions-and-consent