You can find issue-level metadata for an article either by exporting search results from the user interface or in the "biblio" field in the response to an API call for a specific work. For instance:
api.openalex.org/works/W2016949000 -->
"biblio": {
"volume": "48",
"issue": "5",
"first_page": "1064",
"last_page": "1078"