"Growth" in this context means impact to and relevance within the organization. It's mostly a leadership thing.

Essentially, you don't need to micromanage the work that Staff+ Engineers do, but it's critical to stream information to them throughout the week and sync with them once a week to align and calibrate.

If you do this consistently week over week, that engineer will flourish within the organization. If not, they'll continue to work within their domain until they see no more growth opportunities and then they'll leave.

Source: I've been a Principal Engineer for about four years and didn't really grow under some managers who left me alone. Once I found a manager that consistently invested in me I really thrived, and now I'm a Senior Principal Engineer and feel more comfortable in my current role than earlier.