cypress/plugins/index.js with different configuration files.

cypress-plugins-index.js

// promisified fs module
const fs = require('fs-extra')
const path = require('path')

function getConfigurationByFile(file) {
  const pathToConfigFile = path.resolve(__dirname, '../config', `${file}.json`)

  return fs.readJson(pathToConfigFile)
}

// plugins file
module.exports = (on, config) => {
  // accept a configFile value or use qa by default
  const file = config.env.configFile || 'qa'
  console.info('\n> Cypress config:', config);

  return getConfigurationByFile(file)
}