How to set default Locale {locale} on default redirected controller?

Well, On Routes.php you can assign {locale} for the homepage and maybe this easy approach might give you idea for the rest:

PHP Code:

$lang = $this->request->uri->getSegment(1); //this is the language code part.
        if($lang == ''){
            return redirect()->to(site_url('/en'));
        } 


So, it will automatically redirect to your default language, whatever it is..