sql server – how to change “localhost” in MariaDB

I wonder if there is any way to change ‘localhost’ in MariaDB. for example, when you create a user in database, it shows ‘user’@’localhost’
I would like to know how to change ‘localhost’ to any other name. for example, I will be able to create a user in database like the following: ‘user’@’mydomain.com’
by the way, I’m very new in MariaDB and SQL server stuff.
thank you in advance!