How do I style the first two posts of a loop

instead of a counter variable, you can use the build-in loop counter;

as I don’t know how you need to wrap the posts into the individual divs, here just an example structure (only to be used with 5 posts per page):

<div class="col-lg-12">
    <div class="row">

            <?php if ( have_posts() ) : ?>
            <?php if ( in_category( 'Featured' ) ) : /* Start the Featured Loop */ ?>

                <?php while( have_posts() ) : the_post(); ?>

                <?php if( $wp_query->current_post == 0 ) { 
                //open wide column wrapper div// ?>
                <?php } ?>

                <?php if( $wp_query->current_post <= 1 ) { 
                get_template_part( 'content', 'featured' );
                //insert large post// ?>
                <?php } ?>

                <?php if( $wp_query->current_post == 1 || $wp_query->current_post <= 1 && $wp_query->current_post == $wp_query->post_count-1 ) { 
                //close wide column div// ?>
                <?php } ?>

                <?php if( $wp_query->current_post == 2 || $wp_query->current_post <= 1 && $wp_query->current_post == $wp_query->post_count-1 ) { 
                //open narrow column wrapper div// ?>
                <?php } ?>

                <?php if( $wp_query->current_post >= 2 ) { 
                get_template_part( 'content', 'featuredside' );
                //insert small post//?>
                <?php } ?>

                <?php if( $wp_query->current_post == 4 || $wp_query->current_post == $wp_query->post_count-1 ) { 
                //close narrow column div// ?>
                <?php } ?>

                <?php endwhile; ?>

                    <?php endif; ?>

                <?php endif; ?>

    </div> <!--/.row-->
</div> <!--/.col-lg-12-->

this takes care of closing the divs even if ther are less than five posts on the page, and also creates an empty second column if ther are only two or less posts.

caveat: using in_category() at that location might give you unexpected results; try to use a different way of making the loop specific to ‘featured’ posts.

what template file are you working on?