Create different groups for trim the config.yaml

hi there,

I work now since january with home assistant and solved the on or other issue.
but now my config.yaml grows every day I change something.
So I want to save the different config in separate .yamls and only list them in the configuration.yaml.

I dont know what I make wrong, or I have a fallacy.
But is it not possible to create a simple group and link them?

like:
test123: !include test123.yaml

and in the test123.yaml I want to copy then the code from the config.yaml to this new yaml…

Try this : https://www.home-assistant.io/docs/configuration/packages/