In our fysical boards we use tokens to limit the WIP coming from a customer.
These tokens are called "kanban tokens" or "customer tokens". For a detailled description see this explanation https://kanbanize.com/blog/patrick-steyaert-customer-kanban/#_ftn2
The fysical tokens are just post-it's with a special color code.
There are a limited number of these tokens available. If no token is available the customer (or project planners) have to wait for a free token before they can put new issues to the teams.
Is it possible to implement the same technique with JIRA ?