Multiple Instances of Swiper on Same page

multiple_swiper.js

if ($('.swiper-container').length > 0) { //some-slider-wrap-in
    let swiperInstances = [];
    $(".swiper-container").each(function(index, element){ //some-slider-wrap-in
        const $this = $(this);
        $this.addClass("instance-" + index); //instance need to be unique (ex: some-slider)
        $this.parent().find(".swiper-pagination").addClass("pagination-" + index);
        $this.parent().find(".swiper-button-prev").addClass("prev-" + index); //prev must be unique (ex: some-slider-prev)
        $this.parent().find(".swiper-button-next").addClass("next-" + index); //next must be unique (ex: some-slider-next)
        swiperInstances[index] = new Swiper(".instance-" + index, { //instance need to be unique (ex: some-slider)
            // your settings ...
            navigation: {
                prevEl: ".prev-" + index,  //prev must be unique (ex: some-slider-prev)
                nextEl: ".next-" + index, //next must be unique (ex: some-slider-next)
            },
            pagination: {
                el: '.pagination-' + index,
                type: 'bullets',
                clickable: true
            },
        });
    });

    // Now you can call the update on a specific instance in the "swiperInstances" object
    // e.g.
    swiperInstances[3].update();
    //or all of them
    setTimeout(function () {
        for (const slider of swiperInstances) {
            slider.update();
        }
    }, 50);
}


<div class="swiper-container">
    <div class="swiper-wrapper">
        <div class="swiper-slide">Slide 1</div>
        <div class="swiper-slide">Slide 2</div>
        <div class="swiper-slide">Slide 3</div>
    </div>
    <div class="swiper-button-next"></div>
    <div class="swiper-button-prev"></div>
</div>

i think you don't need to pass selectors as pagination and navigation properties, you could just pass HTML elements.
This way you don't need to set classes and you don't need to update instances. Also you will not need to save instances.

Example:

var paginationEl = $this.find(".swiper-pagination")[ 0 ];

Then you can do:

pagination: { el: paginationEl, type: 'bullets', clickable: true }

Type parameter is also not needed, because you are using default option.

Also, this is not need:

if ($('.swiper-container').length > 0) { //some-slider-wrap-in

First you are looping over elements you find here:

$(".swiper-container").each(function(index, element){

So, if there is no element nothing will be run.
Also, you can remove jquery and use plain js. You will have one problem less. :)