Google’s Crawler is indexing all pages listed in your sitemap.xml. On root folder You have to create robots.txt file, and in their content You should specify the path to sitemap.xml.
A deleted page for You means to remove them from CMS, but for search engine means broken links.
Our recommandation is to keep the pages in trash (bin), WordPress’s CMS performs redirects on 404 Page in your Page in moved to recycle bun and informs search engines to remove it from search results.
If you allready permanently removed pages from bin, WordPress will stop management that pages, so You have write redirect rules (301 – moved permanently) in your .htaccess file.
For now Best SEO tool in the market in Yoast SEO, a WordPress plugin).
We still awaiting for Google SiteKit.