You can check your code for Sylius coding standard by running the following command:
$ vendor/bin/ecs check src tests
Some of the violations can be automatically fixed by running the same command with
--fix suffix like:
$ vendor/bin/ecs check src tests --fix
Most of Sylius coding standard checks are extracted to SyliusLabs/CodingStandard package so that reusing them in your own projects or Sylius plugins is effortless. Too learn about details, take a look at its README.