[nickm12]

I'm a staff/principal at a FAANG. My experience agrees with the other answers here that "it depends"—specifically, on what the larger org or team needs from me at the moment. There is a chunk of consistent work, though, which is somewhat of a mix between an engineering manager and an IC.

Like engineering managers, I am responsible for planning out a team's long term goals and reporting on them to senior management. Also like engineering managers I'm responsible for hiring and evaluating technical talent, particularly the senior software engineers in our org plus people who are under consideration for promotion or hiring into my level.

Unlike engineering managers, it's important that I do "hands on" work. This includes my own tech designs and coding, but much more reviewing the designs and code of others. I see my job as delivering technical artifacts through others. What's different between the principal/staff role and the senior eng/tech lead role is the levels of indirection. For a senior eng, you are generally owning the output of a team of people (roughly 3-7 people, though it varies).

At the staff/principal level you work at the level of a team of teams, so your job is really to develop and mentor the tech leads of those teams. Occasionally you might be called in as a tie-breaker or to assist on some cross-team issue, but ideally that doesn't happen too often because the tech leads know their stuff (and they'd better because there is no way you can know the details of multiple team's worth of systems).