Please read topnew/src/Blog/config.ini, config.en.ini etc
Do not change directly on above ini file, instead, you can add at /blog/index.php $init settings eg:

The docs at the config.ini etc should be self explained and easy to understand.

$init = [
// other config init info ...
'att_kb' = 800, // attachment max file size in kb
'markdown' = 1, // use php markdown to render html for topic msg text
// ...
];