Where should I place the sitemap for the fourth level domain?

Where should I place the sitemap.xml file for a fourth-level domain (for example en.subdomain.example.com)?

From sitemaps.org:

All URLs listed in the site map must reside on the same host as the
Sitemap. For example, if the sitemap is at the address
http://www.example.com/sitemap.xml, it cannot include the URLs of
http://subdomain.example.com. If the sitemap is located at
http://www.example.com/myfolder/sitemap.xml, it cannot include URL
at http://www.example.com.

Does this mean that I should place a different sitemap.xml file in the root directory of each subdomain? For example:

example.com/sitemap.xml - for links ~ https://example.com/path
subdomain1.example.com/sitemap.xml - for links ~ https://subdomain1.example.com/path
subdomain2.example.com/sitemap.xml - for links ~ https://subdomain2.example.com/path
en.subdomain1.example.com/sitemap.xml - for links ~ https://en.subdomain1.example.com/path
fr.subdomain2.example.com/sitemap.xml - for links ~ https://fr.subdomain2.example.com/path

Currently, I have a sitemap.xml file at the root of https://example.com/, which includes all of the links for all of the subdomains.