How to consider vars/sample.yml to create a dynamic variable name ?

I have a query regarding vars structure in Ansible.

Example:

-vars

  • sample.yml

  • tasks

  • main.yml

In task:

include_vars: sample.yml

- copy: src={{vars[inventory_hostname_short + ‘_instance’ }} dest={{some_path}}

or

- copy: src={{vars/sample.yml[inventory_hostname_short + ‘_instance’ }} dest={{some_path}}

The above copy command searching for main.yml in vars.

→ How should we consider taking sample.yml instead of vars ??