Intrusive GDPR-dialog script. Variables are used by Statamic, so you might need to define your own. Uses a11y-dialog, linked at the top.

dialog-script.html

<script src="https://cdn.jsdelivr.net/npm/a11y-dialog@5.2.0/a11y-dialog.min.js"></script>
<script async src="https://www.googletagmanager.com/gtag/js?id=ADD-ID-HERE"></script>
<script>
    'use strict';
    var cookieName = 'company-gdpr';
    var redirect = '{{ gdpr_cta_decline_url }}'; // Redirect for decline
    var expiration = {{ gdpr_expiry_time }}; // Expiration time in days
    var animDuration = 200; // Animation duration in milliseconds
    var animDelay = 1000; // Animation duration in milliseconds
    window.ga=window.ga||function(){(ga.q=ga.q||[]).push(arguments)};ga.l=+new Date;
    function initGA() {
        window.dataLayer = window.dataLayer || [];
        function gtag(){dataLayer.push(arguments);}
        gtag('js', new Date());
    
        gtag('config', 'ADD-ID-HERE');
    }
    $(document).ready(function () {
        var dialogEl = document.getElementById('gdpr');
        var mainEl = document.getElementById('main');
        if (dialogEl) {
            var keypressHandler = window.A11yDialog.prototype._bindKeypress;
            var dialog = new window.A11yDialog(dialogEl, mainEl);
            dialog._bindKeypress = function (event) {
                // Capture escape key.
                if (event.key === "Escape" || event.keyCode === 27) return;
                keypressHandler.bind(undefined, event);
            };
            var hideDialog = function hideDialog(element) {
                $(dialogEl).fadeOut(animDuration, function () {
                    dialog.hide();
                });
            };
            var clearCookies = function clearCookies() {
                $.each(Cookies.get(), function (key) {
                    return Cookies.remove(key);
                });
            };
            dialog.on('show', function (dialogEl, triggerEl) {
                $(dialogEl).children(".dialog-wrapper").hide();
                
                setTimeout(function () {
                    $(dialogEl).children(".dialog-wrapper").fadeIn(animDuration);
                    setTimeout(function () {
                        $('#gdpr .dialog-content > div').scrollTop(0);
                    }, 0);
                }, animDelay);
                // Once the accept button is clicked,
                // set the cookie and close dialog
                $(".dialog-accept").click(function (e) {
                    e.preventDefault();
                    Cookies.set(cookieName, true, {
                        expires: expiration,
                        secure: true
                    });
                    hideDialog(dialogEl);
                });
                $(".dialog-decline").click(function (e) {
                    e.preventDefault();
                    hideDialog(dialogEl);
                });
            });
            dialog.on('hide', function () {
                $('body').removeClass('overflow-hidden');
                // The dialog was closed without cookie set
                if (!Cookies.get(cookieName)) {
                    clearCookies();
                    // Redirect to new page on decline
                    window.location = redirect;
                }
                else {
                    initGA();
                }
            });
            // To manually control the dialog:
            if (!Cookies.get(cookieName)) {
                dialog.show();
                $('body').addClass('overflow-hidden');
            }
            else {
                initGA();
            }
        }
        
        // Clear cookies when button with class .gdpr-clear is pushed
        $(".gdpr-clear").click(function (e) {
            e.preventDefault();
    
            clearCookies();
    
            // Redirect to new page on decline
            window.location = redirect;
        });
    });
</script>