RankMath SEO: FAQ block with collapsible headers aka an accordion, see full blog post: https://silvanhagen.com/?p=1125

rankmath-faq-accordion.css

#rank-math-faq .rank-math-list-item {
    margin-bottom: 1em;
    margin-top: 1em;
    border-bottom: 1px solid #fff;
}

.rank-math-question {
    cursor: pointer;
    position: relative;
    display: block;
    padding-right: 1em;
    margin-right: 1em;
    font-weight: 300;
    margin-top: 30px;
}

.rank-math-question:after {
    position: absolute;
    right: 5px;
    top: 0;
    content: "\2715";
    transform: rotate(-45deg);
    transition: all 150ms ease-in-out;
}

.rank-math-question.collapse:after {
    transform: rotate(0deg);
}

.rank-math-question:hover {
    opacity: 0.8;
}

rankmath-faq-accordion.js

(function ($) {

    var rankMath = {
        accordion: function () {
            $('.rank-math-block').find('.rank-math-answer').hide(); // hides all answers by default
            // $('.rank-math-block').find('.rank-math-answer:not(:first)').hide(); // doesn't hide the first item
            $('.rank-math-block').find('.rank-math-question').click(function () {  
                //Expand or collapse this panel
                $(this).nextAll('.rank-math-answer').eq(0).slideToggle('fast', function () {
                    if ($(this).hasClass('collapse')) {
                        $(this).removeClass('collapse');
                    }
                    else {
                        $(this).addClass('collapse');
                    }
                });
                //Hide the other panels
                $(".rank-math-answer").not($(this).nextAll('.rank-math-answer').eq(0)).slideUp('fast');
            });

            $('.rank-math-block .rank-math-question').click(function () {
                $('.rank-math-block .rank-math-question').not($(this)).removeClass('collapse');
                if ($(this).hasClass('collapse')) {
                    $(this).removeClass('collapse');
                }
                else {
                    $(this).addClass('collapse');
                }
            });
        }
    };

    rankMath.accordion();

})(jQuery);