Normally I would but this is for a large network of sitesWhy don't you just make it easier for Google by submitting the sitemap?
best practice is to include it in your robots.txt file. many say do not submit your blackhat site or tier 1s to GSC; this does not mean that you should not have a robots.txt with sitemap url in it.As title says. If I don't register my website in Google search console and submit a sitemap will Google look for /sitemap.xml? Or can I link to it from my homepage or robots file?