Multilingual Sitemap will be automatically available if you are using one of the compatible plugins:
You can find Multilingual Sitemap URL under Settings > XML Sitemaps > General > XML Sitemap section:
Multilingual Sitemap Index will contains all available Sitemap Links, so you can easily add just one URL to the Search Console instead of adding all Sitemaps separately.
Ready Multilingual Sitemap will look like this:
