Advanced Search Form

<form role="search" method="get" action="<?php echo esc_url( home_url( '/' ) ); ?>" class="wp-block-search__button-outside wp-block-search__text-button wp-block-search">

    <label class="wp-block-search__label screen-reader-text" for="wp-block-search__input">Search</label>

    <div class="wp-block-search__inside-wrapper">

    <input class="wp-block-search__input" id="wp-block-search__input" placeholder="Search..." value="<?php echo get_search_query(); ?>" type="search" name="s" required="" minlength="4">

    <!-- Hidden inputs for selected categories -->

    <input type="hidden" name="category_name[]" value="news" />

    <!-- <input type="hidden" name="category_name[]" value="books" /> -->

    <button aria-label="Search" class="wp-block-search__button wp-element-button" type="submit">Search</button>    

    </div>

</form>