JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery-validate/1.19.0/jquery.validate.js"></script>
<form action="{{ route('posts-listing.store') }}" method="POST" class="m-form m-form--label-align-right" id="m_post_submit">
    <div class="modal-body">
        @csrf
        <div class="form-group m-form__group row">
            <label class="col-md-4 col-form-label">Name: <span class="text-danger">*</span></label>
            <div class="col-md-8">
                <input class="form-control m-input" type="text" placeholder="Enter name" name="name" autofocus>
            </div>
        </div>
        <div class="form-group m-form__group row">
            <label class="col-md-4 col-form-label" for="phone_country">Phone Number: <span class="text-danger">*</span></label>
            <div class="col-md-8">
                <div class="input-group m-input-group">
                    <div class="input-group-prepend">
                        <select class="form-control m-bootstrap-select m_selectpicker" name="phone_country" id="phone_country">
                <option value="1" selected title="SK">Slovakia (+421)</option>
                <option data-divider="true"></option>
                <option value="2" title="CZ">Czech (+420)</option>
            </select>
                    </div>
                    <input type="text" class="form-control" id="m_inputmask_phone" name="phone_number" placeholder="Enter phone number">
                </div>
            </div>
        </div>
        <div class="form-group m-form__group row">
            <label class="col-md-4 col-form-label">E-mail address:</label>
            <div class="col-md-8">
                <input class="form-control m-input" type="email" placeholder="Enter your email" name="email" autocomplete="off" required="false">
            </div>
        </div>
        <div class="form-group m-form__group row">
            <label class="col-md-4 col-form-label">Note:</label>
            <div class="col-md-8">
     ...

JavaScript

$(document).ready(function() {

    $('#m_post_submit').validate({
        rules: {
            name: {
                required: true
            },
            phone_number: {
                required: true,
                minlength: 12
            },
            email: {
                required: false
                email: true
            }
        },
        submitHandler: function(form) {
            form.ajaxSubmit({
                type: 'post',
                url: form.attr('action'),
                data: form.serialize(),
                success: function() {
                    btn.removeClass('m-loader m-loader--right m-loader--light').attr('disabled', false);
                    location.reload();
                }
            });
            return false;
        }
    });

});