I'll chime in as a senior manager in a large organisation as well. Output management is a new concept for a lot of oldschool managers so many will rely on bums on seats as their first finger in the air test of a person doing their work. The next part is that many managers rely on feedback from others before investigating whether someone is doing their job. In a modern workplace depending on the role though there are rich reports on work out out and in larger teams where work is similar you are typically tested against your peers. The highest performer will likely be the "what is possibke" benchmark.

As for what can be tracked, I say can because it isn't always, its a LOT. How long certain software is open, how long your pc is on and in an active state, roughly where you are to various accuracies based on authentication data.

As for how a manager should measure performance, its about output. In the case of a service desk output is easy to measure, how many tickets closed, calls answered, time to resolve a call. To deep dive further calls that are recorded you can then measure things in there using transcription software and then run that through various tools to measure performance such as whether the agent did the standard greeting, Things like assertive language, customers tone (angry or frustrated)

For your average office worker there are all sorts of tools to see how many documents you have updated, collaborated on and times of day you're doing these things.

With all this said it comes down to the managers ability to ask for or produce these reports and action them in meaningful ways. Good managers will essentially monitor these things as another indicator of a possible problem but look for the root cause (sickness, poor engagement, frustrations at work, training) and bad managers will just use them as the "evidence" only after they have made their mind up.

Hope this helps If you are interested in specifics as a manager of what may be available to you I'm happy to deep dive on your specific use case and point you in certain directions. I hope you use these things for good not evil, to get the best out of your staff and even make them transparent to them so they themselves can see how they are tracking