Get certificate without linked service

Hello folks,

I'm working on a personal project involving traefik as proxy manager and mailu as SMTP server.
To deal with both, I need to generate a root domain certificate with a sans subdomain (
My project purpose is to create a dynamic bundle with many self-hosted services. That means the user could have a mailu service on a subdomain and any service on the root one. So my question is : Can I get a letsencrypt certificate on the root and subdomain without linked service and keep this certificate even if new service will be bound on the root domain and other ones to the smtp domain.

Hoping my explanation was good enough. Thank's in advance.