Many content management systems have plugins or settings that allow for Site Map generation. For instance, Yoast SEO, SEOPress, Rankmath, All in One SEO, and Google XML Sitemaps are popular WordPress plugins generating sitemaps. A free option to generate a static XML file is to use https://www.xml-sitemaps.com. You can create your sitemap, download it, upload it to your server and then submit the URL to Google. Try a different plugin generator or a static XML sitemap generator if you're running into issues.