mysql -u root -p

mysql> CREATE USER 'test_user'@'localhost' IDENTIFIED BY 'password';
ERROR 1227 (42000): Access denied; you need (at least one of) the CREATE USER privilege(s) for this operation

mysql> GRANT ALL PRIVILEGES ON * . * TO 'user1'@'localhost';
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

mysql> SELECT User,Host FROM mysql.user;
ERROR 1142 (42000): SELECT command denied to user 'root'@'localhost' for table 'user'

mysql> FLUSH PRIVILEGES;
ERROR 1227 (42000): Access denied; you need (at least one of) the RELOAD privilege(s) for this operation

root@sql:~# mysql -u root -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 106596
Server version: 8.0.23 MySQL Community Server - GPL

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Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> GRANT ALL ON *.* TO 'root'@'localhost' WITH GRANT OPTION;
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
mysql>

CREATE USER 'username'@'192.168.%' IDENTIFIED BY 'the_password';
GRANT ALL PRIVILEGES ON *.* TO 'username'@'192.168.%' WITH GRANT OPTION;