Is there any process for username should be updated automatically based on Username format

Summary:

We have setup for username format is person number, when we update the person number (ex: from 1XXXX to 2XXXX), then username also should be updated automatically. (As we have already setup username format is person number).

Kindly suggest is there any process and to achieve this.

Content (required):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):