You can customize the item display template of the CQWP to show more item information.
By default, the XSL style sheet that controls the presentation of the Content By Query Web Part renders item columns. The XSL style sheets are located in site collection Style Library (\Style Library\XSL Style Sheets).
(If the Style Library is missing, check if the publishing features are activated:
1. On the Site Collection Features page, activate SharePoint Server Publishing Infrastructure.
2. On the Site Features page, activate SharePoint Server Publishing.)
Here is a demo about how to display additional fields in CQWP. Export CQWP and change the xml file for each site.
Information about how to customize the HTML editor and the CQWP:
These article also apply to SPO.
Note: Use the managed property of the field and ensure the managed property is retrievable.