Silly and useless straightfoward way to wrap your junk html containeirs in yii2 with a fullscreen functionality
composer install cacko/yii2-widget-fullscreen
use Cacko\Yii2\Widgets\FullScreen\widgets\FullScreenWidget;
echo FullScreenWidget::widget(['content' => Html::img('/start.webp')]);
there's bunch of defaults in Cacko\Yii2\Widgets\FullScreen\components\Options
, as usual if you think they are crap, feel free to inject your own ideas, just keep in mind you will have to bother with the css styles too - good luck