what are some lesser-known tools or features that have significantly enhanced your workflow or crea

Scripting has sped up a bunch of tasks for me. 

But that was ESTK Scripting, which is legacy now, so if you want to look into Scripting it might be better to check out UXP Scripting right away. 

And while this may not be a »lesser-known« feature: Customizing Keyboard Shortcuts was also important to me. 

Having shortcuts for the Filters one uses most often can save some time. 

Data-driven graphics can significantly speed up the process.

The Frame Tool.  I was making labels for my wife who was selling plants when our garden was included in a garden tour.  A grid layout to snap the frames to, and the flower images snap perfectly sized to the selected frame.  It's years since I last use the Frame Tool, but significantly speeded up making these labels.