I noticed by default the frame rate in Unity is 60fps. If I'm doing a timeline sequence that will be rendered out as an image sequence via recorder, should I set the frame rate there to 60 fps? I ask because I would be taking this into After Effects and ideally want my frame rate at 30 fps.
if you select the timeline asset in the project window you can specify the desired framerate for a specific timeline (say 60, 30, 24 etc) https://docs.unity3d.com/Packages/com.unity.timeline@1.2/manual/insp_tl.html Note: this purely affects the visual frame counter on the timeline window itself, everything internally with timeline uses high-precision timers.
the final output fps is determined by the recorder package when you render - again the framerate setting is purely a visual indicator for you on the timeline window. https://unitytech.github.io/unity-recorder/manual/index.html (recorder package is available in package manager)