The wp-config.php file

If you need to update your database credentials, change the website's path, or adjust other core WordPress settings, you can do so directly in wp-config.php.

The file is located in the root directory, and WordPress has excellent documentation on what to change and where. Visit their site for more information:

Example: https://wordpress.org/documentation/article/editing-wp-config-php/

If your theme requires more PHP memory, for example, find "WP_MEMORY_LIMIT" and change it to the desired value:

define( 'WP_MEMORY_LIMIT', '64M' );