You'll need to build the tests you want to perform using load testing tools.
There's a doc on https://confluence.atlassian.com/enterprise/jira-performance-testing-available-tools-729743538.html for doing JIRA and the same basic principles apply to Confluence, although you will need to remember that the data is a very different shape in the two systems.
Ok, you'll need to write some to test what you want to test.
There are some jmeter ones for older versions of JIRA and Confluence that Atlassian used to use, but I'm not aware of any for more recent versions, or if any other users have ones they're willing to share with you for a starting point.
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