I don't know what the "foreign affairs establishment" is supposed to be. In any case, I never watch CNN or BBC.
The government has an opinion. You might call it the 'company line'. That doesn't make it right or wrong. One of the MSNBC talking heads, Richard Haas, makes a nice living from doing it. He writes books that do a really good job at providing an analysis of the challenges we face in foreign affairs. But they aren't so hot at providing a road map for making things better. That would usually include problems America doesn't want to face.
At this point it's easier to disaggregate. You've got the State Dept, which is literally the 'company line'. Along with them there are groups of people, people that often disagree, that contribute to the discussion of what our policy should be. There are the intellectuals, foreign policy academics, think tanks, foreign affairs publications, corporate types, politicians (not many that are influential).
In a real administration (meaning not Trump) a policy gets attention from at least a dozen different departments. The people in the government will want to persuade the top layers, and they will use the work of scholars or think tanks, or even foreigners that agree with them. It's usually a long process because so much has to be considered. However, politics will often provide limits or goals. For example, Biden will have closed off avenues of discussion about staying in Afghanistan at some point.
These things change over time. Ambassadors used to have a lot of power back in the days when a letter from DC could take a month to get there. Now they are tightly constrained by the constant communications from the State Dept, the White House and other agencies. The fact that we go to war more often than we used to also diminishes their influence.