How do I create a lookup pick list where options depend on another column?

I have a table with tasks where one column is a tag via a lookup from another table. Ideally, I would like the options to be filtered based on the project the task belongs to (which is in another column) or even autopopulated for projects that have tags. But I also want to be able to assign tags independent of projects.

I’ve set up a simple mockup of the doc below. Any tips for how I could achieve this?

HI Bjorn,

This image shows how I implemented a filter which does what you are looking for: There is a list of people in my tenant list. (Both people already in a property, and some who are prospective tenants) When I have an empty property, the select will exclude people already in a property, and only show propective tenants.

A live example is below: