Happy to help give some guidance. ??
One quick note, before you make or attempt to make any changes to the database, make sure you create a backup. If something goes wrong, you can revert back. And even better, we’d highly recommend trying this for the first time on a test or staging site, especially if you are unfamiliar with the tasks.
Correct. Under CPanel, you should look for an option phpMyAdmin. My recommendation, your hosting provider should have a help document about accessing phpMyAdmin from their CPanel setup, each one might be slightly different.
Once you get access to phpMyAdmin, you will have access to your Database. Expand open the database table. More than likely, you might see a prefix value, but you need to look for the following:
wp_[prefix]_za_values
wp_[prefix]_za_types
Expand open. Now here is a screenshot as reference.
https://ibb.co/crg5yr4
You will see an entry Description. Right now, it has the varchar(250) set, you need to change this entry value based upon your needs. Do this for both values.
We modified to 500 characters, now the front-end shows 500 characters in the descriptions: https://ibb.co/XxTQtJ5
I hope that helps as a guide. Good luck.