// you could use the invokable flag so you don't use the index

php artisan make:controller PagesController --invokable

// and then use this route:
Route::get('/{any?}', App\Http\Controllers\PagesController::class)->where('any', '.*');

// it tells Laravel routing to respond to any route provided or nothing with the question mark "?" and responds with an invokable controller

    public function __invoke()
    {
        return view('welcome');
    }