In addition, aggregation can be turned off in the UI by navigating to Configuration>Performance (admin/config/development/performance).

When setting up a development environment, change these settings directly in your settings.php file. (This is the preferred method.) The best way to do this is to enable the use of a settings.local.php file. Then put your environment-specific settings into this local file. From there, you can also include the development.services.yml file that comes with core, and use that as a location for your environment-specific services settings.

Take a look at this video: