Gsyfuy

actually i am trying to add quantity increment and decreament (+ and
- button) in minicart magento 2.3.
If anyone have any idea please guide me.

Magento 2 using KnockoutJs for render data in Minicart.
You can override template:
vendor/magento/module-checkout/view/frontend/web/template/minicart/item/default.html

And call to ajax function for update data
checkout/sidebar/updateItemQty/

Or use free module:
https://github.com/php-cuong/magento2-qty

app/design/frontend/Module/theme/Magento_Checkout/web/template/minicart/item/default.html

<div class="product-item-pricing">

                <!-- ko if: canApplyMsrp -->



                <div class="details-map">

                    <span class="label" data-bind="i18n: 'Price'"></span>

                    <span class="value" data-bind="i18n: 'See price before order confirmation.'"></span>

                </div>

                <!-- /ko -->

                <!-- ko ifnot: canApplyMsrp -->

                <!-- ko foreach: $parent.getRegion('priceSidebar') -->

                <!-- ko template: {name: getTemplate(), data: item.product_price, as: 'price'} --><!-- /ko -->

                <!-- /ko -->

                <!-- /ko -->



                <div class="details-qty qty">

                    <label class="label" data-bind="i18n: 'Qty', attr: {

                    for: 'cart-item-'+item_id+'-qty'}"></label>

                    <div class="more">+</div>

                        <input data-bind="attr: {

                        id: 'cart-item-'+item_id+'-qty',

                        'data-cart-item': item_id,

                        'data-item-qty': qty,

                        'data-cart-item-id': product_sku

                        }, value: qty"

                        type="number"

                        size="4"

                        class="item-qty cart-item-qty">



                    <div class="less">-</div>

                    <button data-bind="attr: {

                    id: 'update-cart-item-'+item_id,

                    'data-cart-item': item_id,

                    title: $t('Update')

                    }"

                    class="update-cart-item"

                    style="display: none">

                        <span data-bind="i18n: 'Update'"></span>

                    </button>

                </div>

            </div>

app/design/frontend/Module/theme/Magento_Checkout/templates/cart/minicart.phtml

<script type="text/javascript">

require(["jquery"],function($){

$('body').on("click",".more, .less",function(){

    var obj = $(this);

    var currentQty = obj.siblings('.cart-item-qty').val();

    var iid = obj.siblings('.update-cart-item').attr('data-cart-item');



    if(obj.hasClass('more')){

        var newAdd = parseInt(currentQty)+parseInt(1);

        obj.siblings('.cart-item-qty').val(newAdd);

        obj.siblings('.cart-item-qty').attr('data-item-qty',newAdd);

        //$('#update-cart-item-'+iid).click();

        $('.update-cart-item').show();

    }else{

      if(parseInt(currentQty) > 1)

   {

   var newAdd = parseInt(currentQty)-parseInt(1);

    obj.siblings('.cart-item-qty').val(newAdd); 

    obj.siblings('.cart-item-qty').attr('data-item-qty',newAdd);

    //$('#update-cart-item-'+iid).click();

    $('.update-cart-item').show();



    }

  });

});

</script>

Its working fine for me.

For ajax increment and decrement quantity in minicart you can use the below extension.

https://github.com/kirtinariya1/MinicartAjaxQtyIncrementDecrement