Micromanging is not necessary. They just set the tone and don't hire people who would write anything opposed to their policy [1] which they rarely need to explicitly convey, although they do at times of course. People write things that they really like get rewarded.

"Manufacturing Consent: The Political Economy of the Mass Media" by Edward S. Herman and Noam Chomsky explains how this work with a very large number of examples.

1. https://youtu.be/9RPKH6BVcoM

2. https://www.amazon.com/Manufacturing-Consent-Political-Econo...