Currently there’s no interface exposed for configuring worker filters in the admin UI; you can configure it via the Terraform provider in the boundary_target resource, or you can configure it on the CLI using the -worker-filter option when creating or updating a target (or using API calls directly, of course).
As for worker tags, they can be any K/V pair at all; region and type are some of the more common keys people commonly tag resources with in cloud environments, but you could tag them with info about who administers that portion of Boundary or even what you had for lunch the day you created that worker – it’s completely up to you. You can also leave workers completely untagged if you don’t need tags on them – I run a demo environment with an untagged worker running on a VM and a tagged worker running inside a Kubernetes cluster.