How to use the pattern attribute

This is the documentation for custom attributes:

https://metabox.io/docs/custom-attributes-for-inputs/

In case you want to use pattern, this is a simple example:

'attributes' => array(
    'pattern'   => '[a-zA-Z0-9]+',
),

Here is a good tool that you can see some common patterns:

https://html5pattern.com/

Cool !
Thank’s a lot !