See how the standard Magento_Review module do it:

See how the standard Magento_Review module do it:

So how can we add new custom tab as same review tab
Use a similar layout instructions:
5 posts were split to a new topic: How to place a new tab after the standard tabs on the frontend product view?
See also:
A post was split to a new topic: How to move the “Description” tab to the first (leftmost) place?