Where to set PHP resource limit with FPM mode?

On the PHP configuration->resource limit page, everything is just default. phpinfo() shows the upload limit is only 2M.

For learning purpose, I’d like to know where these default values come from and will I be able to change the default value?

set Maximum file upload size as high as you like (eg. 8M) and also Maximum HTTP POST size to be same value

Thanks for your reply. I didn’t word the question right. I meant to ask where the default values come from. I have updated the question.

php.ini for fpm. eg /etc/php/7.4/fpm/php.ini (if you use php7.4 on debian)
webmin → tools → php configuration, add fpm configuration file path and edit there… that should be the defaults for new domains after the change.