How to connect PHPMailer to Wordpress?

Question

PHPMailer

Greetings! I pulled my layout on cms wordpress, then I wanted to connect work with forms, but I don’t want to use any plugin, because it seemed to me that they heavily load the site and plus there is crap with their styles. I found a vidos on YouTube on which I wrote the codes below, uploaded everything to the hosting, and it gives me the following error: POST multi-faced.tw1.ru/sendmail.php 404 (Not Found). As I understand it, he does not see this file, which means that in js, where FETCH sets the path, you need to specify it correctly somehow, but I don’t understand how. Save me, this is my first time doing this ((

JS code:

function submitForm() {
    document.addEventListener('DOMContentLoaded', function () {
        const form = document.getElementById('form');
        form.addEventListener('submit', formSend);

        async function formSend(e) {
            e.preventDefault();

            let error = formValidate(form);

            let formData = new FormData(form);
            // formData.append('image', formImage.files[0]);

            if (error === 0) {
                form.classList.add('_sending');
                let response = await fetch('sendmail.php', {
                    method: 'POST',
                    body: formData
                });
                if (response.ok) {
                    let result = await response.json();
                    alert(result.message);
                    // formPreview.innerHTML = '';
                    form.reset();
                    form.classList.remove('_sending');
                } else {
                    alert('Ошибка!');
                    form.classList.remove('_sending');
                }
            } else {
                alert('Сначала заполните поле')
            }
        }

        function formValidate(form) {
            let error = 0;
            let formReq = document.querySelectorAll('._req');

            for (let index = 0; index < formReq.length; index++) {
                const input = formReq[index];
                formRemoveError(input);

                if (input.classList.contains('_email')) {
                    if (emailTest(input)) {
                        formAddError(input);
                        error++;
                    }
                } else if (input.getAttribute('type') === 'checkbox' && input.checked === false) {
                    formAddError(input);
                    error++;
                } else {
                    if (input.value === '') {
                        formAddError(input);
                        error++;
                    }
                }
            }
            return error;
        }

        function formAddError(input) {
            input.parentElement.classList.add('_error');
            input.classList.add('_error');
        }
        function formRemoveError(input) {
            input.parentElement.classList.remove('_error');
            input.classList.remove('_error');
        }
        function emailTest(input) {
            return !/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,8})+$/.test(input.value);
        }

        // const formImage = document.getElementById('formImage');
        // const formPreview = document.getElementById('formPreview');

        // formImage.addEventListener('change', () => {
        //     uploadFile(formImage.files[0]);
        // });
        // function uploadFile(file) {
        //     if (!['image/jpeg', 'image/png', 'image/gif'].includes(file.type)) {
        //         alert('Разрешены только изображения');
        //         formImage.value = '';
        //         return;
        //     }
        //     if (file.size > 2 * 1024 * 1024) {
        //         alert('Файл должен быть менее 2 МБ.');
        //         return;
        //     }

        //     let reader = new FileReader();
        //     reader.onload = function (e) {
        //         formPreview.innerHTML = `<img src="${e.target.result}" alt="Фото">`;
        //     };
        //     reader.onerror = function (e) {
        //         alert('Ошибка');
        //     };
        //     reader.readAsDataURL(file);
        // }
    });
}

submitForm();

HTML code:

<form action="#" id="form" class="subscribe__form">
                        <div class="subscribe__input-wrap">
                            <input id="formEmail" placeholder="Type Your Email Address" class="subscribe__input _req _email" type="text" name="email">
                            <div class="subscribe__button-wrap">
                                <button class="subscribe__btn btn" type="submit">Send now</button>
                            </div>
                        </div>
                    </form>

sendmail.php code:

<?php

    use PHPMailer\PHPMailer\PHPMailer;
    use PHPMailer\PHPMailer\Exception;

    require 'phpmailer/src/Exception.php';
    require 'phpmailer/src/PHPMailer.php';

    $mail = new PHPMailer(true);
    $mail->Charset = 'UTF-8';
    $mail->setLanguage('ru', 'phpmailer/language/');
    $mail->IsHTML(true);

    // От кого письмо
    $mail->setForm('[email protected]', 'Фрилансер по жизни');
    //Кому отправить
    $mail->addAddress('[email protected]');
    //Тема письма
    $mail->Subject = 'Привет! Это "Фрилансер по жизни"';

    //Тело письма
    $body = '<h1>Встречайте супер письмо!<h1>';
    if (trim(!empty($_POST['email']))) {
        $body.='<p><strong>E-mail:</strong> '.$_POST['email'].'</p>';
    }

    $mail->Body = $body;

    //Отправляем
    if (!$mail->send()) {
        $message = 'Ошибка';
    } else {
        $message = 'Данные отправлены';
    }

    $response = ['mesaage' => $message];

    header('Content-type: application/json');
    echo json_encode($response);

?>