Currently, we can link issue in JIRA as related JIRA issue link.

The closest feature to JIRA issue link in Confluence are Related Macro however this would require the user to add the label to those related page.

Some company has strict restriction that does not allow them to edit and adding label to those pages therefore the Related Macro is not usable for them. Adding all those label to the related page are also a tedious task which is not user friendly if the user only want to link a few pages as it require them to add the label beforehand.