Yes it is possible.
Aside from the local communities in your instance right now (and using the local timeline), you already have manually to subscribe to every community you want.
You already want to subscribe only to the communities you are interested in, or else you will get too many unwanted posts because the timeline is not cut to fit you like other social media services.
You can use Lemmy community browser to search for communities in all instances.

Debian ou Xubuntu