在plugins-》index.js檔案末尾加上這一塊程式碼，更詳細的內容檢視文件中的plugins相關內容 https://docs.cypress.io/api/plugins/browser-launch-api#Syntax

module.exports = (on, config) => {
    on('before:browser:launch', (browser = {}, launchOptions) => {
        // `args` is an array of all the arguments that will
        // be passed to browsers when it launches
 

        console.log(launchOptions.args) // print all current args

        if (browser.family === 'chromium' && browser.name !== 'electron') {
            // auto open devtools
            launchOptions.args.push('--auto-open-devtools-for-tabs')
        }

        if (browser.family === 'firefox
 
') {
            // auto open devtools
            launchOptions.args.push('-devtools')
        }

        if (browser.name === 'electron') {
            // auto open devtools
            launchOptions.preferences.devTools = true
        }

        // whatever you return here becomes the launchOptions
        return
 
 launchOptions
    })
};