Check the configuration file used on Windows:

Find from Services.msc

1. Open the Services.msc windows.
2. Find the mysql service running and right click on properties.
3. In General tab, you find the executable path where you find the MY.INI file.

"C:\Program Files\MySQL\MySQL Server 8.0\bin\mysqld.exe" --defaults-file="C:\ProgramData\MySQL\MySQL Server 8.0\my.ini" MySQL80

Another way to find from command line of windows:

---It will find the my.ini file location
mysqld --help --verbose --console | findstr "my.ini"

C:\WINDOWS\my.ini 
C:\WINDOWS\my.cnf 
C:\my.ini 
C:\my.cnf 
C:\Program Files\MySQL\MySQL Server 8.0\my.ini 
C:\Program Files\MySQL\MySQL Server 8.0\my.cnf

Check the configuration file On Linux

ps aux |grep mysqld

Check the configuration file on Solaris

$ /usr/ucb/ps -alxwww | grep mysqld