Prevent custom subdomains from indexing

Hi guys,

we want to have 3 domains:

  1. domain.com
  2. staging.domain.com
  3. dev.domain.com

No 1. should be indexed, no. 2-3 should not. My question is how to achieve that. If I put a no index meta tag, it will also prevent domain.com from indexing.

The webflow settings apparently only offer that possibility for their own subdomain xy.webflow.io

Thanks!